diff --git a/kadai1/edm20627/.gitignore b/kadai1/edm20627/.gitignore
new file mode 100644
index 00000000..6ecd33cb
--- /dev/null
+++ b/kadai1/edm20627/.gitignore
@@ -0,0 +1,17 @@
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, built with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+# Dependency directories (remove the comment below to include it)
+# vendor/
+
+.DS_store
diff --git a/kadai1/edm20627/README.md b/kadai1/edm20627/README.md
new file mode 100644
index 00000000..789cb3e5
--- /dev/null
+++ b/kadai1/edm20627/README.md
@@ -0,0 +1,12 @@
+# 画像変換コマンド
+指定ディレクトリ以下の画像ファイルを変換します。
+
+## 使用方法
+
+`cmd --from jpg --to png ディレクトリ`
+
+## オプション
+
+* `--from(-f)` 変換対象の画像形式(デフォルト: jpg)
+* `--to(-t)` 変換後の画像形式(デフォルト: png)
+* `--delete(-d)` 変換前の画像を削除(デフォルト: 無効)
diff --git a/kadai1/edm20627/go.mod b/kadai1/edm20627/go.mod
new file mode 100644
index 00000000..02e3b462
--- /dev/null
+++ b/kadai1/edm20627/go.mod
@@ -0,0 +1,3 @@
+module github.com/edm20627/gopherdojo-studyroom/kadai1/edm20627
+
+go 1.15
diff --git a/kadai1/edm20627/imageconvert/imageconvert.go b/kadai1/edm20627/imageconvert/imageconvert.go
new file mode 100644
index 00000000..f8817128
--- /dev/null
+++ b/kadai1/edm20627/imageconvert/imageconvert.go
@@ -0,0 +1,108 @@
+package imageconvert
+
+import (
+	"errors"
+	"image"
+	"image/gif"
+	"image/jpeg"
+	"image/png"
+	"os"
+	"path/filepath"
+)
+
+// Supported extensions.
+var SupportedFormat = []string{"png", "jpg", "jpeg", "gif"}
+
+type ConvertImage struct {
+	filepaths    []string
+	From, To     string
+	DeleteOption bool
+}
+
+// Get the target files for image conversion.
+func (ci *ConvertImage) Get(dirs []string) error {
+	for _, dir := range dirs {
+		err := filepath.Walk(dir,
+			func(path string, info os.FileInfo, err error) error {
+				if info == nil {
+					return errors.New(path + " is not directory")
+				}
+				if info.IsDir() || filepath.Ext(path)[1:] != ci.From {
+					return nil
+				}
+				ci.filepaths = append(ci.filepaths, path)
+				return nil
+			})
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Perform image conversion.
+func (ci *ConvertImage) Convert() error {
+	for _, path := range ci.filepaths {
+		err := convert(path, ci.To, ci.DeleteOption)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Check for supported extensions.
+func (ci *ConvertImage) Valid() bool {
+	for _, v := range SupportedFormat {
+		if v == ci.From {
+			for _, v := range SupportedFormat {
+				if v == ci.To {
+					return true
+				}
+			}
+		}
+	}
+	return false
+}
+
+func convert(path string, to string, deleteOption bool) error {
+	f, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	img, _, err := image.Decode(f)
+	if err != nil {
+		return err
+	}
+
+	out, err := os.Create(path[:len(path)-len(filepath.Ext(path))+1] + to)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+
+	switch to {
+	case "png":
+		if err := png.Encode(out, img); err != nil {
+			return err
+		}
+	case "jpg", "jpeg":
+		if err := jpeg.Encode(out, img, nil); err != nil {
+			return err
+		}
+	case "gif":
+		if err := gif.Encode(out, img, nil); err != nil {
+			return err
+		}
+	}
+
+	if deleteOption {
+		if err := os.Remove(path); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
diff --git a/kadai1/edm20627/main.go b/kadai1/edm20627/main.go
new file mode 100644
index 00000000..407d2409
--- /dev/null
+++ b/kadai1/edm20627/main.go
@@ -0,0 +1,43 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/edm20627/gopherdojo-studyroom/kadai1/edm20627/imageconvert"
+)
+
+var ci = imageconvert.ConvertImage{}
+
+func init() {
+	flag.StringVar(&ci.From, "-from", "jpg", "Specify the image format before conversion")
+	flag.StringVar(&ci.From, "f", "jpg", "Specify the image format before conversion (short)")
+	flag.StringVar(&ci.To, "-to", "png", "Specify the converted image format")
+	flag.StringVar(&ci.To, "t", "png", "Specify the converted image format (short)")
+	flag.BoolVar(&ci.DeleteOption, "-delete", false, "Delete the image before conversion")
+	flag.BoolVar(&ci.DeleteOption, "d", false, "Delete the image before conversion (short)")
+}
+
+func main() {
+	flag.Parse()
+	dirs := flag.Args()
+
+	if !ci.Valid() {
+		fmt.Fprintln(os.Stderr, "supported formt is "+strings.Join(imageconvert.SupportedFormat, ", "))
+		os.Exit(1)
+	}
+
+	err := ci.Get(dirs)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+
+	err = ci.Convert()
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
diff --git a/kadai1/edm20627/sample_image/hoge/sample3.png b/kadai1/edm20627/sample_image/hoge/sample3.png
new file mode 100644
index 00000000..02908b23
Binary files /dev/null and b/kadai1/edm20627/sample_image/hoge/sample3.png differ
diff --git a/kadai1/edm20627/sample_image/hoge/sample4.png b/kadai1/edm20627/sample_image/hoge/sample4.png
new file mode 100644
index 00000000..fc271cd8
Binary files /dev/null and b/kadai1/edm20627/sample_image/hoge/sample4.png differ
diff --git a/kadai1/edm20627/sample_image/sample.jpg b/kadai1/edm20627/sample_image/sample.jpg
new file mode 100644
index 00000000..dc98d757
Binary files /dev/null and b/kadai1/edm20627/sample_image/sample.jpg differ
diff --git a/kadai1/edm20627/sample_image/sample2.jpg b/kadai1/edm20627/sample_image/sample2.jpg
new file mode 100644
index 00000000..83932905
Binary files /dev/null and b/kadai1/edm20627/sample_image/sample2.jpg differ
diff --git a/kadai2/edm20627/.gitignore b/kadai2/edm20627/.gitignore
new file mode 100644
index 00000000..6ecd33cb
--- /dev/null
+++ b/kadai2/edm20627/.gitignore
@@ -0,0 +1,17 @@
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, built with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+# Dependency directories (remove the comment below to include it)
+# vendor/
+
+.DS_store
diff --git a/kadai2/edm20627/README.md b/kadai2/edm20627/README.md
new file mode 100644
index 00000000..789cb3e5
--- /dev/null
+++ b/kadai2/edm20627/README.md
@@ -0,0 +1,12 @@
+# 画像変換コマンド
+指定ディレクトリ以下の画像ファイルを変換します。
+
+## 使用方法
+
+`cmd --from jpg --to png ディレクトリ`
+
+## オプション
+
+* `--from(-f)` 変換対象の画像形式(デフォルト: jpg)
+* `--to(-t)` 変換後の画像形式(デフォルト: png)
+* `--delete(-d)` 変換前の画像を削除(デフォルト: 無効)
diff --git a/kadai2/edm20627/go.mod b/kadai2/edm20627/go.mod
new file mode 100644
index 00000000..91235c33
--- /dev/null
+++ b/kadai2/edm20627/go.mod
@@ -0,0 +1,3 @@
+module github.com/edm20627/gopherdojo-studyroom/kadai2/edm20627
+
+go 1.15
diff --git a/kadai2/edm20627/go.sum b/kadai2/edm20627/go.sum
new file mode 100644
index 00000000..25c5d358
--- /dev/null
+++ b/kadai2/edm20627/go.sum
@@ -0,0 +1 @@
+github.com/edm20627/gopherdojo-studyroom v0.0.0-20200808023015-dd3cfe05cf7a h1:qrHQJOIqb8bC1Ulkv5H6eGp3DZgRA93eLUJr6XK/Gjk=
diff --git a/kadai2/edm20627/imageconvert/imageconvert.go b/kadai2/edm20627/imageconvert/imageconvert.go
new file mode 100644
index 00000000..775ccee3
--- /dev/null
+++ b/kadai2/edm20627/imageconvert/imageconvert.go
@@ -0,0 +1,117 @@
+package imageconvert
+
+import (
+	"errors"
+	"image"
+	"image/gif"
+	"image/jpeg"
+	"image/png"
+	"os"
+	"path/filepath"
+)
+
+// Supported extensions.
+var SupportedFormat = []string{"png", "jpg", "jpeg", "gif"}
+
+var (
+	ErrNotSpecified = errors.New("Need to specify directory or file")
+	ErrNotDirectory = errors.New("Specify directory or file is not directory")
+)
+
+type ConvertImage struct {
+	Filepaths    []string
+	From, To     string
+	DeleteOption bool
+}
+
+// Get the target files for image conversion.
+func (ci *ConvertImage) Get(dirs []string) error {
+	if len(dirs) == 0 {
+		return ErrNotSpecified
+	}
+
+	for _, dir := range dirs {
+		err := filepath.Walk(dir,
+			func(path string, info os.FileInfo, err error) error {
+				if info == nil {
+					return ErrNotDirectory
+				}
+				if info.IsDir() || filepath.Ext(path)[1:] != ci.From {
+					return nil
+				}
+				ci.Filepaths = append(ci.Filepaths, path)
+				return nil
+			})
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Perform image conversion.
+func (ci *ConvertImage) Convert() error {
+	for _, path := range ci.Filepaths {
+		err := convert(path, ci.To, ci.DeleteOption)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Check for supported extensions.
+func (ci *ConvertImage) Valid() bool {
+	var fromSupported, toSupported bool
+	for _, v := range SupportedFormat {
+		if v == ci.From {
+			fromSupported = true
+		}
+		if v == ci.To {
+			toSupported = true
+		}
+	}
+	return fromSupported && toSupported
+}
+
+func convert(path string, to string, deleteOption bool) error {
+	f, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	img, _, err := image.Decode(f)
+	if err != nil {
+		return err
+	}
+
+	out, err := os.Create(path[:len(path)-len(filepath.Ext(path))+1] + to)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+
+	switch to {
+	case "png":
+		if err := png.Encode(out, img); err != nil {
+			return err
+		}
+	case "jpg", "jpeg":
+		if err := jpeg.Encode(out, img, nil); err != nil {
+			return err
+		}
+	case "gif":
+		if err := gif.Encode(out, img, nil); err != nil {
+			return err
+		}
+	}
+
+	if deleteOption {
+		if err := os.Remove(path); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
diff --git a/kadai2/edm20627/imageconvert/imageconvert_test.go b/kadai2/edm20627/imageconvert/imageconvert_test.go
new file mode 100644
index 00000000..c7ac1d2f
--- /dev/null
+++ b/kadai2/edm20627/imageconvert/imageconvert_test.go
@@ -0,0 +1,215 @@
+package imageconvert_test
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path"
+	"reflect"
+	"strings"
+	"testing"
+
+	"github.com/edm20627/gopherdojo-studyroom/kadai2/edm20627/imageconvert"
+)
+
+func TestGet(t *testing.T) {
+	success_cases := []struct {
+		name      string
+		dirs      []string
+		filepaths []string
+		from      string
+		expected  []string
+	}{
+		{name: "get jpg", dirs: []string{"../testdata"}, from: "jpg", expected: []string{"../testdata/hoge/img_1.jpg", "../testdata/img_1.jpg"}},
+		{name: "get png", dirs: []string{"../testdata"}, from: "png", expected: []string{"../testdata/hoge/img_2.png", "../testdata/img_2.png"}},
+		{name: "get gif", dirs: []string{"../testdata"}, from: "gif", expected: []string{"../testdata/hoge/img_3.gif", "../testdata/img_3.gif"}},
+	}
+
+	for _, c := range success_cases {
+		t.Run(c.name, func(t *testing.T) {
+			ci := imageconvert.ConvertImage{From: c.from}
+			if err := ci.Get(c.dirs); err != nil {
+				t.Error(err)
+			}
+			if !reflect.DeepEqual(ci.Filepaths, c.expected) {
+				t.Errorf("want %v, got %v", c.expected, ci.Filepaths)
+			}
+		})
+	}
+
+	failure_cases := []struct {
+		name      string
+		dirs      []string
+		filepaths []string
+		from      string
+		expected  error
+	}{
+		{name: "occurred ErrNotSpecified", dirs: []string{}, from: "jpg", expected: imageconvert.ErrNotSpecified},
+		{name: "occurred ErrNotDirectory", dirs: []string{"../non_testdata"}, from: "jpg", expected: imageconvert.ErrNotDirectory},
+	}
+
+	for _, c := range failure_cases {
+		t.Run(c.name, func(t *testing.T) {
+			ci := imageconvert.ConvertImage{From: c.from}
+			if err := ci.Get(c.dirs); err != c.expected {
+				t.Errorf("want %v, got %v", c.expected, err)
+			}
+		})
+	}
+}
+
+func TestConvert(t *testing.T) {
+	// テスト実行ディレクトリを作成するためにtastdataをコピー
+	targetDir := "../test_execution_dir"
+	if err := testDirCopy(t, "../testdata", targetDir); err != nil {
+		t.Fatal("Failed to copy the test directory")
+	}
+
+	cases := []struct {
+		name         string
+		filepaths    []string
+		from         string
+		to           string
+		deleteOption bool
+	}{
+		{name: "jpg to png(deleteOption: false)", filepaths: []string{targetDir + "/img_1.jpg"}, from: "jpg", to: "png", deleteOption: false},
+		{name: "png to gif(deleteOption: false)", filepaths: []string{targetDir + "/img_2.png"}, from: "png", to: "gif", deleteOption: false},
+		{name: "gif to jpg(deleteOption: false)", filepaths: []string{targetDir + "/img_3.gif"}, from: "gif", to: "jpg", deleteOption: false},
+		{name: "jpg to png(deleteOption: true)", filepaths: []string{targetDir + "/img_1.jpg"}, from: "jpg", to: "png", deleteOption: true},
+		{name: "png to gif(deleteOption: true)", filepaths: []string{targetDir + "/img_2.png"}, from: "png", to: "gif", deleteOption: true},
+		{name: "gif to jpg(deleteOption: true)", filepaths: []string{targetDir + "/img_3.gif"}, from: "gif", to: "jpg", deleteOption: true},
+	}
+
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+
+			ci := imageconvert.ConvertImage{Filepaths: c.filepaths, To: c.to, DeleteOption: c.deleteOption}
+			if actual := ci.Convert(); actual != nil {
+				t.Error(actual)
+			}
+
+			// ファイルのありなしを確認
+			for _, fileName := range c.filepaths {
+				// 変換前ファイル
+				_, err := os.Stat(fileName)
+				if (err == nil) == c.deleteOption {
+					t.Fatal(err)
+				}
+
+				// 変換後ファイル
+				targetFileName := strings.Replace(fileName, c.from, c.to, 1)
+				_, err = os.Stat(targetFileName)
+				if err != nil {
+					t.Fatal(err)
+				}
+			}
+
+			for _, filepath := range c.filepaths {
+				targetFile := strings.Replace(filepath, c.from, c.to, 1)
+				if err := os.Remove(targetFile); err != nil {
+					t.Fatal(err)
+				}
+			}
+		})
+	}
+
+	// テスト実行ディレクトリを削除
+	if err := os.RemoveAll(targetDir); err != nil {
+		fmt.Println(err)
+	}
+}
+
+func TestValid(t *testing.T) {
+	cases := []struct {
+		name     string
+		from     string
+		to       string
+		expected bool
+	}{
+		{name: "jpg to png (true to true)", from: "jpg", to: "png", expected: true},
+		{name: "png to jpg (true to true)", from: "png", to: "jpg", expected: true},
+		{name: "jpeg to gif (true to true)", from: "jpeg", to: "gif", expected: true},
+		{name: "gif to jpeg (true to true)", from: "gif", to: "jpeg", expected: true},
+		{name: "jpg to fuga (true to false)", from: "jpg", to: "fuga", expected: false},
+		{name: "hoge to jpg (false to true)", from: "hoge", to: "jpg", expected: false},
+		{name: "hoge to fuga (false to false)", from: "hoge", to: "fuga", expected: false},
+	}
+
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			ci := imageconvert.ConvertImage{From: c.from, To: c.to}
+			if actual := ci.Valid(); c.expected != actual {
+				t.Errorf("want %v, got %v", c.expected, actual)
+			}
+		})
+	}
+}
+
+func testDirCopy(t *testing.T, src string, dst string) error {
+	t.Helper()
+	var err error
+	var fds []os.FileInfo
+	var srcinfo os.FileInfo
+
+	if srcinfo, err = os.Stat(src); err != nil {
+		t.Error(err)
+	}
+
+	if err = os.MkdirAll(dst, srcinfo.Mode()); err != nil {
+		t.Error(err)
+
+	}
+
+	if fds, err = ioutil.ReadDir(src); err != nil {
+		t.Error(err)
+
+	}
+
+	for _, fd := range fds {
+		srcfp := path.Join(src, fd.Name())
+		dstfp := path.Join(dst, fd.Name())
+
+		if fd.IsDir() {
+			if err = testDirCopy(t, srcfp, dstfp); err != nil {
+				t.Error(err)
+
+			}
+		} else {
+			if err = testFileCopy(t, srcfp, dstfp); err != nil {
+				t.Error(err)
+
+			}
+		}
+	}
+
+	return nil
+}
+
+func testFileCopy(t *testing.T, src, dst string) error {
+	t.Helper()
+	var err error
+	var srcfd *os.File
+	var dstfd *os.File
+	var srcinfo os.FileInfo
+
+	if srcfd, err = os.Open(src); err != nil {
+		t.Error(err)
+	}
+	defer srcfd.Close()
+
+	if dstfd, err = os.Create(dst); err != nil {
+		t.Error(err)
+	}
+	defer dstfd.Close()
+
+	if _, err = io.Copy(dstfd, srcfd); err != nil {
+		t.Error(err)
+	}
+
+	if srcinfo, err = os.Stat(src); err != nil {
+		t.Error(err)
+	}
+
+	return os.Chmod(dst, srcinfo.Mode())
+}
diff --git a/kadai2/edm20627/main.go b/kadai2/edm20627/main.go
new file mode 100644
index 00000000..1bdb38bb
--- /dev/null
+++ b/kadai2/edm20627/main.go
@@ -0,0 +1,43 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/edm20627/gopherdojo-studyroom/kadai2/edm20627/imageconvert"
+)
+
+var ci = imageconvert.ConvertImage{}
+
+func init() {
+	flag.StringVar(&ci.From, "-from", "jpg", "Specify the image format before conversion")
+	flag.StringVar(&ci.From, "f", "jpg", "Specify the image format before conversion (short)")
+	flag.StringVar(&ci.To, "-to", "png", "Specify the converted image format")
+	flag.StringVar(&ci.To, "t", "png", "Specify the converted image format (short)")
+	flag.BoolVar(&ci.DeleteOption, "-delete", false, "Delete the image before conversion")
+	flag.BoolVar(&ci.DeleteOption, "d", false, "Delete the image before conversion (short)")
+}
+
+func main() {
+	flag.Parse()
+	dirs := flag.Args()
+
+	if !ci.Valid() {
+		fmt.Fprintln(os.Stderr, "supported formt is "+strings.Join(imageconvert.SupportedFormat, ", "))
+		os.Exit(1)
+	}
+
+	err := ci.Get(dirs)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+
+	err = ci.Convert()
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
diff --git a/kadai2/edm20627/sample_image/hoge/sample3.png b/kadai2/edm20627/sample_image/hoge/sample3.png
new file mode 100644
index 00000000..02908b23
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