diff --git a/src/main/java/com/titi/titi_user/adapter/in/web/api/CheckUsernameController.java b/src/main/java/com/titi/titi_auth/adapter/in/web/api/CheckUsernameController.java
similarity index 84%
rename from src/main/java/com/titi/titi_user/adapter/in/web/api/CheckUsernameController.java
rename to src/main/java/com/titi/titi_auth/adapter/in/web/api/CheckUsernameController.java
index 8f42be8..78a1b8a 100644
--- a/src/main/java/com/titi/titi_user/adapter/in/web/api/CheckUsernameController.java
+++ b/src/main/java/com/titi/titi_auth/adapter/in/web/api/CheckUsernameController.java
@@ -1,4 +1,4 @@
-package com.titi.titi_user.adapter.in.web.api;
+package com.titi.titi_auth.adapter.in.web.api;
 
 import org.hibernate.validator.constraints.Length;
 import org.springframework.http.MediaType;
@@ -16,13 +16,13 @@
 import lombok.Builder;
 import lombok.RequiredArgsConstructor;
 
-import com.titi.titi_user.application.port.in.CheckUsernameUseCase;
-import com.titi.titi_user.common.TiTiUserBusinessCodes;
+import com.titi.titi_auth.application.port.in.CheckUsernameUseCase;
+import com.titi.titi_auth.common.TiTiAuthBusinessCodes;
 
 @Validated
 @RestController
 @RequiredArgsConstructor
-class CheckUsernameController implements UserApi {
+public class CheckUsernameController implements AuthApi {
 
 	private final CheckUsernameUseCase checkUsernameUseCase;
 
@@ -31,7 +31,7 @@ class CheckUsernameController implements UserApi {
 	@GetMapping(value = "/members/check", produces = MediaType.APPLICATION_JSON_VALUE)
 	public ResponseEntity<CheckUsernameResponseBody> checkUsername(@NotBlank @Email @Length(max = 30) @RequestParam String username) {
 		final CheckUsernameUseCase.Result result = this.checkUsernameUseCase.invoke(CheckUsernameUseCase.Command.builder().username(username).build());
-		final TiTiUserBusinessCodes businessCodes = result.isPresent() ? TiTiUserBusinessCodes.ALREADY_EXISTS_USERNAME : TiTiUserBusinessCodes.DOES_NOT_EXIST_USERNAME;
+		final TiTiAuthBusinessCodes businessCodes = result.isPresent() ? TiTiAuthBusinessCodes.ALREADY_EXISTS_USERNAME : TiTiAuthBusinessCodes.DOES_NOT_EXIST_USERNAME;
 		return ResponseEntity.status(businessCodes.getStatus())
 			.body(
 				CheckUsernameResponseBody.builder()
diff --git a/src/main/java/com/titi/titi_auth/adapter/out/persistence/FindAccountPortAdapter.java b/src/main/java/com/titi/titi_auth/adapter/out/persistence/FindAccountPortAdapter.java
new file mode 100644
index 0000000..448ec5d
--- /dev/null
+++ b/src/main/java/com/titi/titi_auth/adapter/out/persistence/FindAccountPortAdapter.java
@@ -0,0 +1,26 @@
+package com.titi.titi_auth.adapter.out.persistence;
+
+import java.util.Optional;
+
+import org.springframework.stereotype.Component;
+
+import lombok.RequiredArgsConstructor;
+
+import com.titi.titi_auth.application.port.out.persistence.FindAccountPort;
+import com.titi.titi_auth.data.jpa.entity.mapper.EntityMapper;
+import com.titi.titi_auth.data.jpa.repository.AccountEntityRepository;
+import com.titi.titi_auth.domain.Account;
+
+@Component
+@RequiredArgsConstructor
+public class FindAccountPortAdapter implements FindAccountPort {
+
+	private final AccountEntityRepository accountEntityRepository;
+
+	@Override
+	public Optional<Account> invoke(Account account) {
+		return this.accountEntityRepository.findByEntity(EntityMapper.INSTANCE.toEntity(account))
+			.map(EntityMapper.INSTANCE::toDomain);
+	}
+
+}
diff --git a/src/main/java/com/titi/titi_user/application/port/in/CheckUsernameUseCase.java b/src/main/java/com/titi/titi_auth/application/port/in/CheckUsernameUseCase.java
similarity index 80%
rename from src/main/java/com/titi/titi_user/application/port/in/CheckUsernameUseCase.java
rename to src/main/java/com/titi/titi_auth/application/port/in/CheckUsernameUseCase.java
index cff0193..96ecf65 100644
--- a/src/main/java/com/titi/titi_user/application/port/in/CheckUsernameUseCase.java
+++ b/src/main/java/com/titi/titi_auth/application/port/in/CheckUsernameUseCase.java
@@ -1,4 +1,4 @@
-package com.titi.titi_user.application.port.in;
+package com.titi.titi_auth.application.port.in;
 
 import lombok.Builder;
 
@@ -20,4 +20,4 @@ record Result(
 
 	}
 
-}
+}
\ No newline at end of file
diff --git a/src/main/java/com/titi/titi_auth/application/port/out/persistence/FindAccountPort.java b/src/main/java/com/titi/titi_auth/application/port/out/persistence/FindAccountPort.java
new file mode 100644
index 0000000..6102b09
--- /dev/null
+++ b/src/main/java/com/titi/titi_auth/application/port/out/persistence/FindAccountPort.java
@@ -0,0 +1,11 @@
+package com.titi.titi_auth.application.port.out.persistence;
+
+import java.util.Optional;
+
+import com.titi.titi_auth.domain.Account;
+
+public interface FindAccountPort {
+
+	Optional<Account> invoke(Account account);
+
+}
diff --git a/src/main/java/com/titi/titi_auth/application/service/CheckUsernameService.java b/src/main/java/com/titi/titi_auth/application/service/CheckUsernameService.java
new file mode 100644
index 0000000..a0948f5
--- /dev/null
+++ b/src/main/java/com/titi/titi_auth/application/service/CheckUsernameService.java
@@ -0,0 +1,25 @@
+package com.titi.titi_auth.application.service;
+
+import org.springframework.stereotype.Service;
+
+import lombok.RequiredArgsConstructor;
+
+import com.titi.titi_auth.application.port.in.CheckUsernameUseCase;
+import com.titi.titi_auth.application.port.out.persistence.FindAccountPort;
+import com.titi.titi_auth.domain.Account;
+
+@Service
+@RequiredArgsConstructor
+public class CheckUsernameService implements CheckUsernameUseCase {
+
+	private final FindAccountPort findAccountPort;
+
+	@Override
+	public Result invoke(Command command) {
+		final Account account = Account.builder().username(command.username()).build();
+		return CheckUsernameUseCase.Result.builder()
+			.isPresent(this.findAccountPort.invoke(account).isPresent())
+			.build();
+	}
+
+}
diff --git a/src/main/java/com/titi/titi_auth/common/TiTiAuthBusinessCodes.java b/src/main/java/com/titi/titi_auth/common/TiTiAuthBusinessCodes.java
index 241ff4f..2d1d77c 100644
--- a/src/main/java/com/titi/titi_auth/common/TiTiAuthBusinessCodes.java
+++ b/src/main/java/com/titi/titi_auth/common/TiTiAuthBusinessCodes.java
@@ -13,6 +13,8 @@ public enum TiTiAuthBusinessCodes {
 	MISMATCHED_AUTH_CODE(200, "AU1003", "The authentication code does not match."),
 	REISSUE_ACCESS_TOKEN_SUCCESS(200, "AU1004", "Successfully reissued the Access Token."),
 	REISSUE_ACCESS_TOKEN_FAILURE_INVALID_REFRESH_TOKEN(200, "AU1005", "The Refresh Token is invalid, so the reissuance of the Access Token has failed."),
+	DOES_NOT_EXIST_USERNAME(200, "AU1006", "The username does not exist."),
+	ALREADY_EXISTS_USERNAME(200, "AU1007", "The username already exists."),
 
 	GENERATE_AUTH_CODE_FAILURE(500, "AU7000", "Failed to generate and transmit the authentication code. Please try again later."),
 	VERIFY_AUTH_CODE_FAILURE(500, "AU7001", "Authentication code verification failed. Please try again later."),
diff --git a/src/main/java/com/titi/titi_auth/data/jpa/entity/AccountEntity.java b/src/main/java/com/titi/titi_auth/data/jpa/entity/AccountEntity.java
new file mode 100644
index 0000000..4b959c0
--- /dev/null
+++ b/src/main/java/com/titi/titi_auth/data/jpa/entity/AccountEntity.java
@@ -0,0 +1,45 @@
+package com.titi.titi_auth.data.jpa.entity;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.EnumType;
+import jakarta.persistence.Enumerated;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import lombok.AccessLevel;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+import com.titi.infrastructure.persistence.jpa.entity.BaseEntity;
+import com.titi.titi_auth.domain.AccountStatus;
+import com.titi.titi_auth.domain.Authority;
+
+@Entity(name = "accounts")
+@Getter
+@Builder(toBuilder = true)
+@AllArgsConstructor(access = AccessLevel.PROTECTED)
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+public class AccountEntity extends BaseEntity {
+
+	@Id
+	@GeneratedValue(strategy = GenerationType.IDENTITY)
+	private Long id;
+
+	@Column(nullable = false)
+	private String username;
+
+	@Column(nullable = false)
+	private String password;
+
+	@Enumerated(value = EnumType.STRING)
+	@Column(nullable = false)
+	private Authority authority;
+
+	@Enumerated(value = EnumType.STRING)
+	@Column(nullable = false)
+	private AccountStatus accountStatus;
+
+}
diff --git a/src/main/java/com/titi/titi_auth/data/jpa/entity/mapper/EntityMapper.java b/src/main/java/com/titi/titi_auth/data/jpa/entity/mapper/EntityMapper.java
new file mode 100644
index 0000000..62897d9
--- /dev/null
+++ b/src/main/java/com/titi/titi_auth/data/jpa/entity/mapper/EntityMapper.java
@@ -0,0 +1,18 @@
+package com.titi.titi_auth.data.jpa.entity.mapper;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.factory.Mappers;
+
+import com.titi.titi_auth.data.jpa.entity.AccountEntity;
+import com.titi.titi_auth.domain.Account;
+
+@Mapper
+public interface EntityMapper {
+
+	EntityMapper INSTANCE = Mappers.getMapper(EntityMapper.class);
+
+	AccountEntity toEntity(Account account);
+
+	Account toDomain(AccountEntity accountEntity);
+
+}
diff --git a/src/main/java/com/titi/titi_auth/data/jpa/repository/AccountEntityRepository.java b/src/main/java/com/titi/titi_auth/data/jpa/repository/AccountEntityRepository.java
new file mode 100644
index 0000000..28c2887
--- /dev/null
+++ b/src/main/java/com/titi/titi_auth/data/jpa/repository/AccountEntityRepository.java
@@ -0,0 +1,10 @@
+package com.titi.titi_auth.data.jpa.repository;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import com.titi.titi_auth.data.jpa.entity.AccountEntity;
+import com.titi.titi_auth.data.jpa.repository.querydsl.AccountEntityQuerydsl;
+
+public interface AccountEntityRepository extends JpaRepository<AccountEntity, Long>, AccountEntityQuerydsl {
+
+}
diff --git a/src/main/java/com/titi/titi_auth/data/jpa/repository/querydsl/AccountEntityQuerydsl.java b/src/main/java/com/titi/titi_auth/data/jpa/repository/querydsl/AccountEntityQuerydsl.java
new file mode 100644
index 0000000..e322600
--- /dev/null
+++ b/src/main/java/com/titi/titi_auth/data/jpa/repository/querydsl/AccountEntityQuerydsl.java
@@ -0,0 +1,11 @@
+package com.titi.titi_auth.data.jpa.repository.querydsl;
+
+import java.util.Optional;
+
+import com.titi.titi_auth.data.jpa.entity.AccountEntity;
+
+public interface AccountEntityQuerydsl {
+
+	Optional<AccountEntity> findByEntity(AccountEntity accountEntity);
+
+}
diff --git a/src/main/java/com/titi/titi_auth/data/jpa/repository/querydsl/AccountEntityQuerydslImpl.java b/src/main/java/com/titi/titi_auth/data/jpa/repository/querydsl/AccountEntityQuerydslImpl.java
new file mode 100644
index 0000000..be06732
--- /dev/null
+++ b/src/main/java/com/titi/titi_auth/data/jpa/repository/querydsl/AccountEntityQuerydslImpl.java
@@ -0,0 +1,52 @@
+package com.titi.titi_auth.data.jpa.repository.querydsl;
+
+import static com.titi.titi_auth.data.jpa.entity.QAccountEntity.*;
+
+import java.util.Optional;
+
+import org.springframework.stereotype.Repository;
+
+import com.querydsl.core.types.dsl.BooleanExpression;
+import com.querydsl.jpa.impl.JPAQueryFactory;
+import lombok.RequiredArgsConstructor;
+
+import com.titi.titi_auth.data.jpa.entity.AccountEntity;
+
+@Repository
+@RequiredArgsConstructor
+public class AccountEntityQuerydslImpl implements AccountEntityQuerydsl {
+
+	private final JPAQueryFactory jpaQueryFactory;
+
+	@Override
+	public Optional<AccountEntity> findByEntity(AccountEntity entity) {
+		return Optional.ofNullable(
+			jpaQueryFactory
+				.selectFrom(accountEntity)
+				.where(
+					idEq(entity),
+					usernameEq(entity),
+					authorityEq(entity),
+					accountStatusEq(entity)
+				)
+				.fetchOne()
+		);
+	}
+
+	private BooleanExpression idEq(AccountEntity entity) {
+		return entity.getId() != null ? accountEntity.id.eq(entity.getId()) : null;
+	}
+
+	private BooleanExpression usernameEq(AccountEntity entity) {
+		return entity.getUsername() != null ? accountEntity.username.eq(entity.getUsername()) : null;
+	}
+
+	private BooleanExpression authorityEq(AccountEntity entity) {
+		return entity.getAuthority() != null ? accountEntity.authority.eq(entity.getAuthority()) : null;
+	}
+
+	private BooleanExpression accountStatusEq(AccountEntity entity) {
+		return entity.getAccountStatus() != null ? accountEntity.accountStatus.eq(entity.getAccountStatus()) : null;
+	}
+
+}
diff --git a/src/main/java/com/titi/titi_auth/domain/Account.java b/src/main/java/com/titi/titi_auth/domain/Account.java
new file mode 100644
index 0000000..c190b22
--- /dev/null
+++ b/src/main/java/com/titi/titi_auth/domain/Account.java
@@ -0,0 +1,14 @@
+package com.titi.titi_auth.domain;
+
+import lombok.Builder;
+
+@Builder
+public record Account(
+	Long id,
+	String username,
+	String password,
+	Authority authority,
+	AccountStatus accountStatus
+) {
+
+}
diff --git a/src/main/java/com/titi/titi_auth/domain/AccountStatus.java b/src/main/java/com/titi/titi_auth/domain/AccountStatus.java
new file mode 100644
index 0000000..2ef61d1
--- /dev/null
+++ b/src/main/java/com/titi/titi_auth/domain/AccountStatus.java
@@ -0,0 +1,33 @@
+package com.titi.titi_auth.domain;
+
+public enum AccountStatus {
+	/**
+	 * The account is in a normal and usable state. <br/>
+	 * The account owner can log in and access the application.
+	 */
+	ACTIVATED,
+	/**
+	 * An account exists but is in an unusable state. <br/>
+	 * This could be a temporary condition, or it might occur when the account owner deactivates the account without deleting it. <br/>
+	 * Inactive accounts are typically eligible for reactivation.
+	 */
+	DEACTIVATED,
+	/**
+	 * The account is temporarily suspended. <br/>
+	 * This can occur due to security issues, payment problems, or transitions to a dormant state. <br/>
+	 * In this state, the account owner cannot access the application.
+	 */
+	SUSPENDED,
+	/**
+	 * The account is permanently suspended. <br/>
+	 * This can occur due to violations of the terms of service, among other reasons. <br/>
+	 * In this state, the account owner cannot access the application.
+	 */
+	BLOCKED,
+	/**
+	 * The account has been permanently deleted. <br/>
+	 * This typically occurs when the account owner initiates the deletion or when an administrator removes the account. <br/>
+	 * Deleted accounts cannot be reactivated.
+	 */
+	DELETED
+}
diff --git a/src/main/java/com/titi/titi_auth/domain/Authority.java b/src/main/java/com/titi/titi_auth/domain/Authority.java
new file mode 100644
index 0000000..6287eb7
--- /dev/null
+++ b/src/main/java/com/titi/titi_auth/domain/Authority.java
@@ -0,0 +1,5 @@
+package com.titi.titi_auth.domain;
+
+public enum Authority {
+	MEMBER, ADMIN
+}
diff --git a/src/main/java/com/titi/titi_user/application/service/CheckUsernameService.java b/src/main/java/com/titi/titi_user/application/service/CheckUsernameService.java
deleted file mode 100644
index c19d8af..0000000
--- a/src/main/java/com/titi/titi_user/application/service/CheckUsernameService.java
+++ /dev/null
@@ -1,25 +0,0 @@
-package com.titi.titi_user.application.service;
-
-import org.springframework.stereotype.Service;
-
-import lombok.RequiredArgsConstructor;
-
-import com.titi.titi_user.application.port.in.CheckUsernameUseCase;
-import com.titi.titi_user.application.port.out.persistence.FindMemberPort;
-import com.titi.titi_user.domain.member.Member;
-
-@Service
-@RequiredArgsConstructor
-class CheckUsernameService implements CheckUsernameUseCase {
-
-	private final FindMemberPort findMemberPort;
-
-	@Override
-	public Result invoke(Command command) {
-		final Member member = Member.builder().username(command.username()).build();
-		return Result.builder()
-			.isPresent(this.findMemberPort.invoke(member).isPresent())
-			.build();
-	}
-
-}
diff --git a/src/main/java/com/titi/titi_user/common/TiTiUserBusinessCodes.java b/src/main/java/com/titi/titi_user/common/TiTiUserBusinessCodes.java
index 25661ec..cfb0a08 100644
--- a/src/main/java/com/titi/titi_user/common/TiTiUserBusinessCodes.java
+++ b/src/main/java/com/titi/titi_user/common/TiTiUserBusinessCodes.java
@@ -7,8 +7,6 @@
 @AllArgsConstructor
 public enum TiTiUserBusinessCodes {
 
-	DOES_NOT_EXIST_USERNAME(200, "USR1000", "The username does not exist."),
-	ALREADY_EXISTS_USERNAME(200, "USR1001", "The username already exists."),
 	REGISTER_MEMBER_SUCCESS(200, "USR1002", "Successfully completed the regular membership registration."),
 	REGISTER_MEMBER_FAILURE_INVALID_AUTH_TOKEN(200, "USR1003", "The registration has failed due to an invalid Auth Token."),
 	REGISTER_MEMBER_FAILURE_ALREADY_EXISTS_USERNAME(200, "USR1004", "The registration has failed as the username already exists."),
diff --git a/src/test/java/com/titi/titi_user/adapter/in/web/api/CheckUsernameControllerTest.java b/src/test/java/com/titi/titi_auth/adapter/in/web/api/CheckUsernameControllerTest.java
similarity index 83%
rename from src/test/java/com/titi/titi_user/adapter/in/web/api/CheckUsernameControllerTest.java
rename to src/test/java/com/titi/titi_auth/adapter/in/web/api/CheckUsernameControllerTest.java
index 01d9f47..52112c9 100644
--- a/src/test/java/com/titi/titi_user/adapter/in/web/api/CheckUsernameControllerTest.java
+++ b/src/test/java/com/titi/titi_auth/adapter/in/web/api/CheckUsernameControllerTest.java
@@ -1,4 +1,4 @@
-package com.titi.titi_user.adapter.in.web.api;
+package com.titi.titi_auth.adapter.in.web.api;
 
 import static org.mockito.ArgumentMatchers.*;
 import static org.mockito.BDDMockito.*;
@@ -19,8 +19,8 @@
 import org.springframework.test.web.servlet.MockMvc;
 import org.springframework.test.web.servlet.ResultActions;
 
-import com.titi.titi_user.application.port.in.CheckUsernameUseCase;
-import com.titi.titi_user.common.TiTiUserBusinessCodes;
+import com.titi.titi_auth.application.port.in.CheckUsernameUseCase;
+import com.titi.titi_auth.common.TiTiAuthBusinessCodes;
 
 @WebMvcTest(controllers = CheckUsernameController.class)
 class CheckUsernameControllerTest {
@@ -33,13 +33,13 @@ class CheckUsernameControllerTest {
 
 	private static Stream<Arguments> whenSuccessToCheckUsername() {
 		return Stream.of(
-			Arguments.of(false, TiTiUserBusinessCodes.DOES_NOT_EXIST_USERNAME),
-			Arguments.of(true, TiTiUserBusinessCodes.ALREADY_EXISTS_USERNAME)
+			Arguments.of(false, TiTiAuthBusinessCodes.DOES_NOT_EXIST_USERNAME),
+			Arguments.of(true, TiTiAuthBusinessCodes.ALREADY_EXISTS_USERNAME)
 		);
 	}
 
 	private ResultActions mockCheckUsername(String username) throws Exception {
-		return mockMvc.perform(get("/api/user/members/check")
+		return mockMvc.perform(get("/api/auth/members/check")
 			.queryParam("username", username)
 			.accept(MediaType.APPLICATION_JSON)
 			.with(csrf()));
@@ -48,7 +48,7 @@ private ResultActions mockCheckUsername(String username) throws Exception {
 	@ParameterizedTest
 	@MethodSource
 	@WithMockUser
-	void whenSuccessToCheckUsername(boolean isPresent, TiTiUserBusinessCodes businessCodes) throws Exception {
+	void whenSuccessToCheckUsername(boolean isPresent, TiTiAuthBusinessCodes businessCodes) throws Exception {
 		// given
 		given(checkUsernameUseCase.invoke(any())).willReturn(CheckUsernameUseCase.Result.builder().isPresent(isPresent).build());
 		final String username = "test@gmail.com";
diff --git a/src/test/java/com/titi/titi_auth/adapter/out/persistence/FindAccountPortAdapterTest.java b/src/test/java/com/titi/titi_auth/adapter/out/persistence/FindAccountPortAdapterTest.java
new file mode 100644
index 0000000..2a0f974
--- /dev/null
+++ b/src/test/java/com/titi/titi_auth/adapter/out/persistence/FindAccountPortAdapterTest.java
@@ -0,0 +1,65 @@
+package com.titi.titi_auth.adapter.out.persistence;
+
+import static org.assertj.core.api.Assertions.*;
+import static org.mockito.ArgumentMatchers.*;
+import static org.mockito.BDDMockito.*;
+
+import java.util.Optional;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import com.titi.titi_auth.data.jpa.entity.AccountEntity;
+import com.titi.titi_auth.data.jpa.repository.AccountEntityRepository;
+import com.titi.titi_auth.domain.Account;
+import com.titi.titi_auth.domain.AccountStatus;
+import com.titi.titi_auth.domain.Authority;
+
+@ExtendWith(MockitoExtension.class)
+class FindAccountPortAdapterTest {
+
+	@Mock
+	private AccountEntityRepository accountEntityRepository;
+
+	@InjectMocks
+	private FindAccountPortAdapter findAccountPortAdapter;
+
+	@Test
+	void whenAccountEntityIsPresent() {
+		// given
+		final String username = "test@gmail.com";
+		final AccountEntity mockAccountEntity = AccountEntity.builder()
+			.id(1L)
+			.username(username)
+			.password("password")
+			.accountStatus(AccountStatus.ACTIVATED)
+			.authority(Authority.MEMBER)
+			.build();
+		given(accountEntityRepository.findByEntity(any())).willReturn(Optional.of(mockAccountEntity));
+
+		// when
+		final Account account = Account.builder().username(username).build();
+		final Optional<Account> result = findAccountPortAdapter.invoke(account);
+
+		// then
+		assertThat(result.isPresent()).isTrue();
+	}
+
+	@Test
+	void whenAccountEntityIsEmpty() {
+		// given
+		final String username = "test@gmail.com";
+		given(accountEntityRepository.findByEntity(any())).willReturn(Optional.empty());
+
+		// when
+		final Account account = Account.builder().username(username).build();
+		final Optional<Account> result = findAccountPortAdapter.invoke(account);
+
+		// then
+		assertThat(result.isEmpty()).isTrue();
+	}
+
+}
\ No newline at end of file
diff --git a/src/test/java/com/titi/titi_auth/adapter/out/persistence/querydsl/AccountEntityQuerydslImplTest.java b/src/test/java/com/titi/titi_auth/adapter/out/persistence/querydsl/AccountEntityQuerydslImplTest.java
new file mode 100644
index 0000000..8bad52d
--- /dev/null
+++ b/src/test/java/com/titi/titi_auth/adapter/out/persistence/querydsl/AccountEntityQuerydslImplTest.java
@@ -0,0 +1,72 @@
+package com.titi.titi_auth.adapter.out.persistence.querydsl;
+
+import static org.assertj.core.api.Assertions.*;
+
+import java.util.Optional;
+
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+
+import com.titi.JpaTestBase;
+import com.titi.titi_auth.data.jpa.entity.AccountEntity;
+import com.titi.titi_auth.data.jpa.repository.AccountEntityRepository;
+import com.titi.titi_auth.data.jpa.repository.querydsl.AccountEntityQuerydslImpl;
+import com.titi.titi_auth.domain.AccountStatus;
+import com.titi.titi_auth.domain.Authority;
+
+class AccountEntityQuerydslImplTest extends JpaTestBase {
+
+	@Autowired
+	private AccountEntityRepository accountEntityRepository;
+
+	@Autowired
+	private AccountEntityQuerydslImpl accountEntityQuerydsl;
+
+	@Nested
+	class FindByEntity {
+
+		@Test
+		void success() {
+			// given
+			final AccountEntity savedEntity = accountEntityRepository.save(
+				AccountEntity.builder()
+					.username("test@gmail.com")
+					.password("password")
+					.accountStatus(AccountStatus.ACTIVATED)
+					.authority(Authority.MEMBER)
+					.build()
+			);
+
+			// when
+			final AccountEntity entity = AccountEntity.builder()
+				.id(savedEntity.getId())
+				.username(savedEntity.getUsername())
+				.authority(savedEntity.getAuthority())
+				.build();
+			final Optional<AccountEntity> result = accountEntityQuerydsl.findByEntity(entity);
+
+			// then
+			assertThat(result.isPresent()).isTrue();
+		}
+
+		@Test
+		void fail() {
+			// given
+			final AccountEntity entity = AccountEntity.builder()
+				.id(1L)
+				.username("test@gmail.com")
+				.accountStatus(AccountStatus.ACTIVATED)
+				.authority(Authority.MEMBER)
+				.build();
+
+			// when
+			final Optional<AccountEntity> result = accountEntityQuerydsl.findByEntity(entity);
+
+			// then
+			assertThat(result.isEmpty()).isTrue();
+		}
+
+	}
+
+}
\ No newline at end of file
diff --git a/src/test/java/com/titi/titi_user/application/service/CheckUsernameServiceTest.java b/src/test/java/com/titi/titi_auth/application/service/CheckUsernameServiceTest.java
similarity index 64%
rename from src/test/java/com/titi/titi_user/application/service/CheckUsernameServiceTest.java
rename to src/test/java/com/titi/titi_auth/application/service/CheckUsernameServiceTest.java
index 38c7218..2256aa8 100644
--- a/src/test/java/com/titi/titi_user/application/service/CheckUsernameServiceTest.java
+++ b/src/test/java/com/titi/titi_auth/application/service/CheckUsernameServiceTest.java
@@ -1,7 +1,9 @@
-package com.titi.titi_user.application.service;
+package com.titi.titi_auth.application.service;
 
 import static org.assertj.core.api.Assertions.*;
+import static org.mockito.ArgumentMatchers.*;
 import static org.mockito.BDDMockito.*;
+import static org.mockito.Mockito.*;
 
 import java.util.Optional;
 
@@ -11,26 +13,25 @@
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
-import com.titi.titi_user.application.port.in.CheckUsernameUseCase;
-import com.titi.titi_user.application.port.out.persistence.FindMemberPort;
-import com.titi.titi_user.domain.member.Member;
+import com.titi.titi_auth.application.port.in.CheckUsernameUseCase;
+import com.titi.titi_auth.application.port.out.persistence.FindAccountPort;
+import com.titi.titi_auth.domain.Account;
 
 @ExtendWith(MockitoExtension.class)
 class CheckUsernameServiceTest {
-
 	@Mock
-	private FindMemberPort findMemberPort;
+	private FindAccountPort findAccountPort;
 
 	@InjectMocks
 	private CheckUsernameService checkUsernameService;
 
 	@Test
-	void whenMemberIsPresentWithUsernameThenReturnTrue() {
-	    // given
+	void whenAccountIsPresentWithUsernameThenReturnTrue() {
+		// given
 		final String username = "test@gmail.com";
-		given(findMemberPort.invoke(any())).willReturn(Optional.of(mock(Member.class)));
+		given(findAccountPort.invoke(any())).willReturn(Optional.of(mock(Account.class)));
 
-	    // when
+		// when
 		final CheckUsernameUseCase.Result result = checkUsernameService.invoke(CheckUsernameUseCase.Command.builder().username(username).build());
 
 		// then
@@ -40,16 +41,15 @@ void whenMemberIsPresentWithUsernameThenReturnTrue() {
 
 	@Test
 	void whenMemberIsNotPresentWithUsernameThenReturnFalse() {
-	    // given
+		// given
 		final String username = "test@gmail.com";
-		given(findMemberPort.invoke(any())).willReturn(Optional.empty());
+		given(findAccountPort.invoke(any())).willReturn(Optional.empty());
 
-	    // when
+		// when
 		final CheckUsernameUseCase.Result result = checkUsernameService.invoke(CheckUsernameUseCase.Command.builder().username(username).build());
 
 		// then
 		assertThat(result).isNotNull();
 		assertThat(result.isPresent()).isFalse();
 	}
-
 }
\ No newline at end of file