diff --git a/go.mod b/go.mod
new file mode 100644
index 00000000..d7d65458
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,11 @@
+module gopherdojo-studyroom
+
+go 1.19
+
+require (
+	github.com/kisielk/errcheck v1.6.2 // indirect
+	github.com/yuin/goldmark v1.4.13 // indirect
+	golang.org/x/mod v0.7.0 // indirect
+	golang.org/x/sys v0.3.0 // indirect
+	golang.org/x/tools v0.4.0 // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 00000000..f69bdcab
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,35 @@
+github.com/kisielk/errcheck v1.6.2 h1:uGQ9xI8/pgc9iOoCe7kWQgRE6SBTrCGmTSf0LrEtY7c=
+github.com/kisielk/errcheck v1.6.2/go.mod h1:nXw/i/MfnvRHqXa7XXmQMUB0oNFGuBrNI8d8NLy0LPw=
+github.com/yuin/goldmark v1.4.1/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
+github.com/yuin/goldmark v1.4.13 h1:fVcFKWvrslecOb/tg+Cc05dkeYx540o0FuFt3nUVDoE=
+github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/mod v0.6.0-dev.0.20220106191415-9b9b3d81d5e3/go.mod h1:3p9vT2HGsQu2K1YbXdKPJLVgG5VJdoTa1poYQBtP1AY=
+golang.org/x/mod v0.7.0 h1:LapD9S96VoQRhi/GrNTqeBJFrUjs5UHCAtTlgwA5oZA=
+golang.org/x/mod v0.7.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
+golang.org/x/net v0.0.0-20211015210444-4f30a5c0130f/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20211019181941-9d821ace8654/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.3.0 h1:w8ZOecv6NaNa/zC8944JTU3vz4u6Lagfk4RPQxv92NQ=
+golang.org/x/sys v0.3.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.1.10/go.mod h1:Uh6Zz+xoGYZom868N8YTex3t7RhtHDBrE8Gzo9bV56E=
+golang.org/x/tools v0.4.0 h1:7mTAgkunk3fr4GAloyyCasadO6h9zSsQZbwvcaIciV4=
+golang.org/x/tools v0.4.0/go.mod h1:UE5sM2OK9E/d67R0ANs2xJizIymRP5gJU295PvKXxjQ=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
diff --git a/kadai1/kenboo0426/README.md b/kadai1/kenboo0426/README.md
new file mode 100644
index 00000000..d36daaa3
--- /dev/null
+++ b/kadai1/kenboo0426/README.md
@@ -0,0 +1,12 @@
+## Options
+
+| Options | Default | Description |
+|--------|--------|---------------------|
+| -path | ./ | convert extension under the path |
+| -from | jpg | image extension before conversion |
+| -to | png | image extension after conversion |
+
+## Usage
+```bash
+$ go run main.go -path=hoge -from=jpg -to=png
+```
\ No newline at end of file
diff --git a/kadai1/kenboo0426/imgconv/convert.go b/kadai1/kenboo0426/imgconv/convert.go
new file mode 100644
index 00000000..e44abc8a
--- /dev/null
+++ b/kadai1/kenboo0426/imgconv/convert.go
@@ -0,0 +1,77 @@
+package imgconv
+
+import (
+	"fmt"
+	"image"
+	"image/gif"
+	"image/jpeg"
+	"image/png"
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// 画像の拡張子を変更する
+func ConvertExtensions(dirpath string, from_ex string, to_ex string) {
+	err := filepath.Walk(dirpath, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if ext := strings.Replace(filepath.Ext(path), ".", "", -1); info.IsDir() || ext != from_ex {
+			return nil
+		}
+
+		convert(path, to_ex)
+		return nil
+	})
+
+	if err != nil {
+		panic(err)
+	}
+}
+
+func convert(before_path string, to_ex string) {
+	before_ex := strings.Replace(filepath.Ext(before_path), ".", "", -1)
+	after_path := strings.Replace(before_path, before_ex, to_ex, -1)
+	f, err := os.Open(before_path)
+	defer func() {
+		if err := f.Close(); err != nil {
+			log.Fatal(err)
+		}
+	}()
+	if err != nil {
+		fmt.Println("open:", err)
+		return
+	}
+	img, _, err := image.Decode(f)
+	if err != nil {
+		fmt.Println("decode:", err)
+		return
+	}
+	fso, err := os.Create(after_path)
+	defer func() {
+		if err := fso.Close(); err != nil {
+			log.Fatal(err)
+		}
+	}()
+	if err != nil {
+		fmt.Println("create:", err)
+		return
+	}
+
+	switch before_ex {
+	case "jpeg", "jpg":
+		err = jpeg.Encode(fso, img, &jpeg.Options{})
+	case "png":
+		err = png.Encode(fso, img)
+	case "gif":
+		err = gif.Encode(fso, img, &gif.Options{})
+	default:
+		fmt.Println("その変換前の形式は対応していません")
+	}
+	if err != nil {
+		fmt.Println("encode:", err)
+	}
+}
diff --git a/kadai1/kenboo0426/main.go b/kadai1/kenboo0426/main.go
new file mode 100644
index 00000000..7bfbc235
--- /dev/null
+++ b/kadai1/kenboo0426/main.go
@@ -0,0 +1,20 @@
+package main
+
+import (
+	"flag"
+	"gopherdojo-studyroom/kadai1/kenboo0426/imgconv"
+	"log"
+)
+
+func main() {
+	dirpath := flag.String("path", "/", "Enter the path")
+	from := flag.String("from", "jpg", "Enter the img extension before conversion")
+	to := flag.String("to", "png", "Enter the img extension after conversion")
+	flag.Parse()
+
+	if dirpath == nil {
+		log.Fatal("Enter the path")
+	}
+
+	imgconv.ConvertExtensions(*dirpath, *from, *to)
+}