diff --git a/kadai2/miyahara/.gitignore b/kadai2/miyahara/.gitignore
new file mode 100644
index 0000000..f32e31a
--- /dev/null
+++ b/kadai2/miyahara/.gitignore
@@ -0,0 +1,2 @@
+.idea/
+.DS_Store
diff --git a/kadai2/miyahara/README.md b/kadai2/miyahara/README.md
new file mode 100644
index 0000000..41417e9
--- /dev/null
+++ b/kadai2/miyahara/README.md
@@ -0,0 +1,22 @@
+# 画像変換コマンド
+## 課題内容
+- 次の仕様を満たすコマンドを作って下さい
+    - ディレクトリを指定する
+    - 指定したディレクトリ以下のJPGファイルをPNGに変換（デフォルト）
+    - ディレクトリ以下は再帰的に処理する
+    - 変換前と変換後の画像形式を指定できる（オプション）
+- 以下を満たすように開発してください
+    - mainパッケージと分離する
+    - 自作パッケージと標準パッケージと準標準パッケージのみ使う
+    - 準標準パッケージ：golang.org/x以下のパッケージ
+    - ユーザ定義型を作ってみる
+    - GoDocを生成してみる
+
+## 実行方法
+実行するために以下のコマンドを実行してください。
+```
+go build -o conv
+./conv -i=[input file type] -o=[output file type] [target directory]
+
+```
+`input file type` と`output file type` はjpgかpngを選択してください。
\ No newline at end of file
diff --git a/kadai2/miyahara/converter/TestData/jpg/testData.jpg b/kadai2/miyahara/converter/TestData/jpg/testData.jpg
new file mode 100755
index 0000000..0893cbf
Binary files /dev/null and b/kadai2/miyahara/converter/TestData/jpg/testData.jpg differ
diff --git a/kadai2/miyahara/converter/TestData/png/testData.png b/kadai2/miyahara/converter/TestData/png/testData.png
new file mode 100755
index 0000000..30081ce
Binary files /dev/null and b/kadai2/miyahara/converter/TestData/png/testData.png differ
diff --git a/kadai2/miyahara/converter/converter.go b/kadai2/miyahara/converter/converter.go
new file mode 100644
index 0000000..d3655f5
--- /dev/null
+++ b/kadai2/miyahara/converter/converter.go
@@ -0,0 +1,139 @@
+package converter
+
+import (
+	"errors"
+	"fmt"
+	"image"
+	"image/jpeg"
+	"image/png"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// Converter Convert jpg to png or png to jpg.
+// In represent a input file type.
+// Out represent a output file type.
+// Directory represent a target directory.
+type Converter struct {
+	in        string
+	out       string
+	directory string
+}
+
+// FileSet is Set of input file name and output file name.
+type FileSet struct {
+	inputFileName  string
+	outputFileName string
+}
+
+// New return a new Converter.
+func New(in, out, directory string) *Converter {
+	return &Converter{in: in, out: out, directory: directory}
+}
+
+// Run execute image convert function.
+func (c Converter) Run() int {
+	var err error
+	fileSetSlice, err := c.dirWalk()
+	if err != nil {
+		fmt.Println(err)
+		return 1
+	}
+	err = c.convert(fileSetSlice)
+	if err != nil {
+		fmt.Println(err)
+		return 1
+	}
+	return 0
+}
+
+// dirWalk returns file set of input file name and output file in target directory.
+func (c Converter) dirWalk() ([]FileSet, error) {
+	fileSetSlice := make([]FileSet, 0, 50)
+	err := filepath.Walk(c.directory, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if filepath.Ext(info.Name()) == ("." + c.in) {
+			inputFileName := path
+			outputFileName := c.outputFilePath(inputFileName)
+			fileSet := FileSet{inputFileName: inputFileName, outputFileName: outputFileName}
+			fmt.Println(inputFileName, outputFileName)
+			fileSetSlice = append(fileSetSlice, fileSet)
+		}
+		return nil
+	})
+
+	if err != nil {
+		return nil, err
+	}
+
+	return fileSetSlice, nil
+}
+
+// convert calls execute function every file set.
+func (c Converter) convert(fileSetSlice []FileSet) error {
+	var err error
+
+	for _, fileSet := range fileSetSlice {
+		err = c.execute(fileSet)
+		if err != nil {
+			break
+		}
+	}
+
+	return err
+}
+
+// execute function open file and calls encode function.
+func (c Converter) execute(fileset FileSet) error {
+	var err error
+
+	inputFile, err := os.Open(fileset.inputFileName)
+	defer inputFile.Close()
+	if err != nil {
+		return err
+	}
+
+	outputFile, err := os.Create(fileset.outputFileName)
+	defer outputFile.Close()
+	if err != nil {
+		return err
+	}
+
+	img, _, err := image.Decode(inputFile)
+	if err != nil {
+		return err
+	}
+
+	err = c.encode(outputFile, img)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// encode returns error by encode function.
+// if output type is not support, Encode returns error.
+func (c Converter) encode(file *os.File, image image.Image) error {
+	switch c.out {
+	case "jpg", "jpeg":
+		err := jpeg.Encode(file, image, &jpeg.Options{Quality: 80})
+		return err
+	case "png":
+		err := png.Encode(file, image)
+		return err
+	default:
+		return errors.New("invalid output type")
+	}
+}
+
+// outputFilePath returns output file path to correspond input file path.
+func (c Converter) outputFilePath(inputFileName string) string {
+	stringSlice := strings.Split(inputFileName, ".")
+	outputFileName := stringSlice[0] + "." + c.out
+	return outputFileName
+}
diff --git a/kadai2/miyahara/converter/converter_test.go b/kadai2/miyahara/converter/converter_test.go
new file mode 100644
index 0000000..8a42ead
--- /dev/null
+++ b/kadai2/miyahara/converter/converter_test.go
@@ -0,0 +1,315 @@
+package converter
+
+import (
+	"image"
+	"os"
+	"reflect"
+	"testing"
+)
+
+func TestNew(t *testing.T) {
+	cases := map[string]struct {
+		in        string
+		out       string
+		directory string
+	}{
+		"success": {
+			in:        "inputFileName",
+			out:       "outputFileName",
+			directory: "targetDirectory",
+		},
+	}
+
+	for n, tc := range cases {
+		tc := tc
+		t.Run(n, func(t *testing.T) {
+			converter := New(tc.in, tc.out, tc.directory)
+			if converter.in != tc.in {
+				t.Errorf("want %s,but actual %s\n", tc.in, converter.in)
+			}
+
+			if converter.out != tc.out {
+				t.Errorf("want %s,but actual %s\n", tc.in, converter.out)
+			}
+
+			if converter.directory != tc.directory {
+				t.Errorf("want %s, but actual %s\n", tc.directory, converter.directory)
+			}
+		})
+	}
+}
+
+func TestConverter_Run(t *testing.T) {
+	cases := map[string]struct {
+		converter Converter
+		expectInt int
+	}{
+		"success": {
+			converter: Converter{in: "jpg", out: "png", directory: "TestData/jpg"},
+			expectInt: 0,
+		},
+		"failed": {
+			converter: Converter{in: "jpg", out: "png", directory: "test"},
+			expectInt: 1,
+		},
+	}
+
+	for n, tc := range cases {
+		tc := tc
+		t.Run(n, func(t *testing.T) {
+			actualInt := tc.converter.Run()
+			if actualInt != tc.expectInt {
+				t.Errorf("want %d, but actual %d", tc.expectInt, actualInt)
+			}
+		})
+	}
+}
+
+func TestConverter_Convert(t *testing.T) {
+	cases := map[string]struct {
+		converter Converter
+		fileSet   []FileSet
+		errBool   bool
+	}{
+		"success": {
+			converter: Converter{in: "jpg", out: "png"},
+			fileSet: []FileSet{
+				{
+					inputFileName:  "TestData/jpg/testData.jpg",
+					outputFileName: "TestData/jpg/testOutput.png",
+				},
+			},
+			errBool: false,
+		},
+		"error": {
+			converter: Converter{in: "jpg", out: "png"},
+			fileSet: []FileSet{
+				{
+					inputFileName:  "test",
+					outputFileName: "test",
+				},
+			},
+			errBool: true,
+		},
+	}
+
+	for n, tc := range cases {
+		tc := tc
+		t.Run(n, func(t *testing.T) {
+			err := tc.converter.convert(tc.fileSet)
+			actualErrBool := err != nil
+			if actualErrBool != tc.errBool {
+				t.Errorf("want %t,but actual %t\n", tc.errBool, actualErrBool)
+			}
+		})
+	}
+}
+
+func TestConverter_Execute(t *testing.T) {
+	cases := map[string]struct {
+		converter Converter
+		fileSet   FileSet
+		errBool   bool
+	}{
+		"success": {
+			converter: Converter{in: "jpg", out: "png"},
+			fileSet: FileSet{
+				inputFileName:  "TestData/jpg/testData.jpg",
+				outputFileName: "TestData/jpg/testOutput.png",
+			},
+			errBool: false,
+		},
+		"failed to open input file": {
+			converter: Converter{in: "jpg", out: "png"},
+			fileSet: FileSet{
+				inputFileName:  "test",
+				outputFileName: "testData/jpg/testOutput.png",
+			},
+			errBool: true,
+		},
+		"failed to open output file": {
+			converter: Converter{in: "jpg", out: "png"},
+			fileSet: FileSet{
+				inputFileName:  "test",
+				outputFileName: "testData/jpg/testOutput.png",
+			},
+			errBool: true,
+		},
+	}
+
+	for n, tc := range cases {
+		tc := tc
+		t.Run(n, func(t *testing.T) {
+			err := tc.converter.execute(tc.fileSet)
+			actualErrBool := err != nil
+			if actualErrBool != tc.errBool {
+				t.Errorf("want %t,but actual %t\n", tc.errBool, actualErrBool)
+			}
+		})
+	}
+}
+
+func TestConverter_Encode(t *testing.T) {
+	cases := map[string]struct {
+		converter      Converter
+		inputFileName  string
+		outputFileName string
+	}{
+		"jpg to png": {
+			converter:      Converter{out: "png"},
+			inputFileName:  "TestData/jpg/testData.jpg",
+			outputFileName: "TestData/jpg/testOutput.png",
+		},
+		"png to jpeg": {
+			converter:      Converter{out: "jpeg"},
+			inputFileName:  "TestData/png/testData.png",
+			outputFileName: "TestData/png/testOutput.jpg",
+		},
+	}
+
+	for n, tc := range cases {
+		tc := tc
+		t.Run(n, func(t *testing.T) {
+			var err error
+
+			outputFile := testCreateFile(t, tc.outputFileName)
+			defer outputFile.Close()
+
+			inputFile := testOpenFile(t, tc.inputFileName)
+			defer inputFile.Close()
+
+			convertImage, _, err := image.Decode(inputFile)
+			if err != nil {
+				t.Error(err)
+			}
+
+			err = tc.converter.encode(outputFile, convertImage)
+			if err != nil {
+				t.Error(err)
+			}
+
+			file := testOpenFile(t, tc.outputFileName)
+			defer file.Close()
+
+			_, actual, err := image.Decode(file)
+			if err != nil {
+				t.Error(err)
+			}
+
+			if tc.converter.out != actual {
+				t.Errorf("want %s, but actual %s\n", tc.converter.out, actual)
+			}
+		})
+	}
+}
+
+func TestConverter_EncodeErr(t *testing.T) {
+	cases := map[string]struct {
+		converter Converter
+		expectErr string
+	}{
+		"error": {
+			converter: Converter{out: "error"},
+			expectErr: "invalid output type",
+		},
+	}
+
+	for n, tc := range cases {
+		tc := tc
+		t.Run(n, func(t *testing.T) {
+			err := tc.converter.encode(nil, nil)
+			if err.Error() != tc.expectErr {
+				t.Errorf("want %s,but actual %s\n", tc.expectErr, err.Error())
+			}
+		})
+	}
+
+}
+
+func TestConverter_OutputFilePath(t *testing.T) {
+	cases := map[string]struct {
+		converter      Converter
+		inputFileName  string
+		outputFileName string
+	}{
+		"jpg to png": {
+			converter:      Converter{out: "png"},
+			inputFileName:  "/test/test.jpg",
+			outputFileName: "/test/test.png",
+		},
+		"png to jpg": {
+			converter:      Converter{out: "jpg"},
+			inputFileName:  "test/test.png",
+			outputFileName: "test/test.jpg",
+		},
+	}
+
+	for n, tc := range cases {
+		tc := tc
+		t.Run(n, func(t *testing.T) {
+			actual := tc.converter.outputFilePath(tc.inputFileName)
+			if tc.outputFileName != actual {
+				t.Errorf("want %s, but actual %s\n", tc.outputFileName, actual)
+			}
+		})
+	}
+
+}
+
+func TestConverter_DirWalk(t *testing.T) {
+	cases := map[string]struct {
+		converter    Converter
+		fileSetSlice []FileSet
+		errBool      bool
+	}{
+		"testData Dir": {
+			converter: Converter{in: "jpg", out: "png", directory: "./TestData/jpg"},
+			fileSetSlice: []FileSet{
+				{
+					inputFileName:  "TestData/jpg/testData.jpg",
+					outputFileName: "TestData/jpg/testOutput.png",
+				},
+			},
+			errBool: false,
+		},
+		"not exist directory": {
+			converter:    Converter{in: "jpg", out: "png", directory: "test"},
+			fileSetSlice: nil,
+			errBool:      true,
+		},
+	}
+
+	for n, tc := range cases {
+		tc := tc
+		t.Run(n, func(t *testing.T) {
+			actual, err := tc.converter.dirWalk()
+			if tc.fileSetSlice != nil {
+				if !reflect.DeepEqual(tc.fileSetSlice[0], actual[0]) {
+					t.Errorf("want %v ,but actual %v\n", tc.fileSetSlice[0], actual[0])
+				}
+			}
+			actualErrBool := err != nil
+			if tc.errBool != actualErrBool {
+				t.Errorf("want %t, but actual %t\n", tc.errBool, actualErrBool)
+			}
+		})
+	}
+}
+
+func testOpenFile(t *testing.T, fileName string) *os.File {
+	t.Helper()
+	file, err := os.Open(fileName)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return file
+}
+
+func testCreateFile(t *testing.T, fileName string) *os.File {
+	t.Helper()
+	file, err := os.Create(fileName)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return file
+}
diff --git a/kadai2/miyahara/main.go b/kadai2/miyahara/main.go
new file mode 100644
index 0000000..1c861e5
--- /dev/null
+++ b/kadai2/miyahara/main.go
@@ -0,0 +1,31 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"github.com/gopherdojo/dojo4/kadai2/miyahara/converter"
+	"os"
+)
+
+var (
+	inputFile  = flag.String("i", "jpg", "input image type")
+	outputFile = flag.String("o", "png", "output image type")
+)
+
+func usage() {
+	fmt.Fprint(os.Stderr, "usage: conv -i=[input file type] -o=[output file type] [target directory]\n")
+	flag.PrintDefaults()
+}
+
+func main() {
+	flag.Usage = usage
+	flag.Parse()
+
+	if flag.NArg() == 0 {
+		fmt.Fprint(os.Stderr, "error: specify target directory\n")
+		os.Exit(2)
+	}
+
+	converter := converter.New(*inputFile, *outputFile, flag.Arg(0))
+	os.Exit(converter.Run())
+}