diff --git a/kadai3/yuuyamad/.gitignore b/kadai3/yuuyamad/.gitignore
new file mode 100644
index 0000000..2464dd9
--- /dev/null
+++ b/kadai3/yuuyamad/.gitignore
@@ -0,0 +1 @@
+./idea
diff --git a/kadai3/yuuyamad/README.md b/kadai3/yuuyamad/README.md
new file mode 100644
index 0000000..50de4b8
--- /dev/null
+++ b/kadai3/yuuyamad/README.md
@@ -0,0 +1,20 @@
+# go concurrent downloader
+
+## Command Line Options
+
+### -p num
+split ratio to download file
+
+### -o filename
+output file to filename
+
+## example
+./yuuyamad -p 20 -o hoge.tar.xz "https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.6.3.tar.xz"
+
+
+## 疑問点
+requestsメソッドをgoroutineで実行する時にcontextをわたしているのだが、１つのgoroutineがtimeoutしたりキャンセル処理された時に
+同じcontextを渡して実行されているgoroutineにもキャンセルが伝播してcontextのDoneチャネルが返るのかなと考えて実装しました
+
+timeoutが他のgoroutineに伝播しているかというのは上手く検証できず、、自信がないのでもし認識間違いなどあれば教えて頂きたいです。
+
diff --git a/kadai3/yuuyamad/log.go b/kadai3/yuuyamad/log.go
new file mode 100644
index 0000000..9053696
--- /dev/null
+++ b/kadai3/yuuyamad/log.go
@@ -0,0 +1,13 @@
+package main
+
+import (
+	"log"
+	"os"
+)
+
+func logError(err error){
+	if err != nil{
+		log.Fatal(err)
+		os.Exit(1)
+	}
+}
\ No newline at end of file
diff --git a/kadai3/yuuyamad/main.go b/kadai3/yuuyamad/main.go
new file mode 100644
index 0000000..e18e9a8
--- /dev/null
+++ b/kadai3/yuuyamad/main.go
@@ -0,0 +1,151 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"golang.org/x/sync/errgroup"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"strconv"
+	"time"
+)
+
+type Range struct {
+	low    int
+	high   int
+	worker int
+}
+
+type Downloader struct {
+	procs    int
+	filename string
+	url      string
+}
+
+func main() {
+
+	var (
+		procs  = flag.Int("p", 10, "split ratio to download file")
+		output = flag.String("o", "", "output filename")
+	)
+
+	flag.Parse()
+	args := flag.Args()
+
+	downloder := Downloader{}
+	downloder.procs = *procs
+	downloder.filename = *output
+	downloder.url = args[0]
+
+	err := downloder.download()
+	if err != nil {
+		logError(err)
+	}
+
+	//分割ダウンロードしたファイルを結合する
+	fh, err := os.Create(downloder.filename)
+	if err != nil {
+		logError(err)
+	}
+	defer fh.Close()
+
+	for j := 0; j < downloder.procs; j++ {
+		f := fmt.Sprintf("%s.%d", downloder.filename, j)
+		subfp, err := os.Open(f)
+		if err != nil {
+			logError(err)
+		}
+
+		io.Copy(fh, subfp)
+
+		subfp.Close()
+		if err := os.Remove(f); err != nil {
+			logError(err)
+		}
+	}
+}
+func (d *Downloader) download() error {
+
+	// contents Headerを取得する
+	res, err := http.Head(d.url)
+	if err != nil {
+		return err
+	}
+
+	maps := res.Header
+	length, err := strconv.Atoi(maps["Content-Length"][0])
+
+	len_sub := length / d.procs
+	diff := length % d.procs
+
+	// errorGroup
+	grp, ctx := errgroup.WithContext(context.Background())
+	ctx, cancel := context.WithTimeout(ctx, 30*time.Second)
+	defer cancel()
+
+	for i := 0; i < d.procs; i++ {
+
+		min := len_sub * i
+		max := len_sub * (i + 1)
+
+		r := Range{}
+		r.low = min
+		r.high = max
+		r.worker = i
+
+		if i == (d.procs - 1) {
+			max += diff
+		}
+		// execute get request
+		grp.Go(func() error {
+			return d.requests(ctx, r)
+		})
+	}
+	if err := grp.Wait(); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (d *Downloader) requests(ctx context.Context, r Range) error {
+	body := make([]string, 99)
+	client := &http.Client{}
+	req, err := http.NewRequest("GET", d.url, nil)
+	if err != nil {
+		return err
+	}
+
+	range_header := "bytes=" + strconv.Itoa(r.low) + "-" + strconv.Itoa(r.high-1)
+	req.Header.Add("Range", range_header)
+
+	errCh := make(chan error, 1)
+	tmpfile := d.filename + "." + strconv.Itoa(r.worker)
+
+	go func() {
+		resp, err := client.Do(req)
+		defer resp.Body.Close()
+
+		reader, err := ioutil.ReadAll(resp.Body)
+		body[r.worker] = string(reader)
+
+		err = ioutil.WriteFile(tmpfile, []byte(string(body[r.worker])), 0x777)
+		errCh <- err
+	}()
+
+	select {
+	case err := <-errCh:
+		if err != nil {
+			return err
+		}
+	case <-ctx.Done():
+		fmt.Printf("requests: %s\n", ctx.Err())
+		os.Remove(tmpfile)
+		<-errCh
+		return ctx.Err()
+
+	}
+	return nil
+}