diff --git a/array/README.md b/array/README.md
deleted file mode 100644
index be7bbf5..0000000
--- a/array/README.md
+++ /dev/null
@@ -1,12 +0,0 @@
-## array.go
-
-配列
-
-## slice.go
-
-スライス
-
-## append.go
-
-append関数の使い方や仕組み
-
diff --git a/array/append.go b/array/append.go
deleted file mode 100644
index cda34dd..0000000
--- a/array/append.go
+++ /dev/null
@@ -1,24 +0,0 @@
-package main
-
-import "fmt"
-
-func main() {
-	ary := []int{}
-	for i := 0; i < 10; i++ {
-		ary = append(ary, i)
-		fmt.Printf("%d: %p len:%d cap:%d %v\n", i, ary, len(ary), cap(ary), ary)
-	}
-	/*
-	   0: 0x140000180b8 len:1 cap:1 [0]
-	   1: 0x140000180e0 len:2 cap:2 [0 1]
-	   2: 0x1400001e040 len:3 cap:4 [0 1 2]
-	   3: 0x1400001e040 len:4 cap:4 [0 1 2 3]
-	   4: 0x14000014100 len:5 cap:8 [0 1 2 3 4]
-	   5: 0x14000014100 len:6 cap:8 [0 1 2 3 4 5]
-	   6: 0x14000014100 len:7 cap:8 [0 1 2 3 4 5 6]
-	   7: 0x14000014100 len:8 cap:8 [0 1 2 3 4 5 6 7]
-	   8: 0x1400006e000 len:9 cap:16 [0 1 2 3 4 5 6 7 8]
-	   9: 0x1400006e000 len:10 cap:16 [0 1 2 3 4 5 6 7 8 9]
-	*/
-}
-
diff --git a/array/array.go b/array/array.go
deleted file mode 100644
index 9cd6461..0000000
--- a/array/array.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package main
-
-import "fmt"
-
-func main() {
-	var a[3]int // 要素の値を省略したらゼロ値
-	fmt.Printf("a: %+v\n", a) // [0, 0, 0]
-	b := [3]int{1, 2, 3}
-	fmt.Printf("b: %+v\n", b) // [1, 2, 3]
-	c := [3]int{1, 2}
-	fmt.Printf("c: %+v\n", c) // [1, 2, 0]
-	d := [3]int{2: 2}
-	fmt.Printf("d: %+v\n", d) // [0, 0, 2]
-	e := [3]int{0:1, 1: 2}
-	fmt.Printf("e: %+v\n", e) // [1, 2, 0]
-
-	// 要素が比較可能であればその配列型も比較可能
-	fmt.Printf("a==b: %v\n", a == b) // false
-	fmt.Printf("c==e: %v\n", c == e) // true
-	// f := [4]int{}
-	// fmt.Printf("a==f: %v\n", a == f) // compile error: [3]int == [4]int
-
-	hoge(a)
-	fmt.Printf("a: %+v\n", a) // [0, 0, 0]
-	// 値渡しなので安全だが性能的に非効率なことがある
-}
-
-func hoge(arg [3]int) { 
-	arg[0] = 4
-	fmt.Printf("%+v\n", arg) // [4, 0, 0]
-}
diff --git a/array/slice.go b/array/slice.go
deleted file mode 100644
index 705cb07..0000000
--- a/array/slice.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package main
-
-import "fmt"
-
-func main() {
-	s := []string{0:"", 1:"Jan", 2:"Feb", 3:"Mar", 4:"Apr", 5:"May", 6:"Jun", 7:"Jul", 8:"Aug", 9:"Sep", 10:"Oct", 11:"Nov", 12:"Dec"}
-	fmt.Printf("%d\n", len(s)) // 13(0-12)
-	fmt.Printf("%+v\n", s[2:4]) // [Feb Mar]
-	fmt.Printf("%d\n", len(s[2:4])) // 2
-	fmt.Printf("%d\n", cap(s[2:4])) // 11(2-12)
-	fmt.Printf("%+v\n", s[2:7]) // [Feb Mar Apr May Jun]
-	fmt.Printf("%d\n", len(s[2:7])) // 5
-	fmt.Printf("%d\n", cap(s[2:7])) // 11(2-12)
-	fmt.Printf("%+v\n", s[:]) // [ Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec]
-}
-
diff --git a/collection/README.md b/collection/README.md
new file mode 100644
index 0000000..be7bbf5
--- /dev/null
+++ b/collection/README.md
@@ -0,0 +1,12 @@
+## array.go
+
+配列
+
+## slice.go
+
+スライス
+
+## append.go
+
+append関数の使い方や仕組み
+
diff --git a/collection/append.go b/collection/append.go
new file mode 100644
index 0000000..cda34dd
--- /dev/null
+++ b/collection/append.go
@@ -0,0 +1,24 @@
+package main
+
+import "fmt"
+
+func main() {
+	ary := []int{}
+	for i := 0; i < 10; i++ {
+		ary = append(ary, i)
+		fmt.Printf("%d: %p len:%d cap:%d %v\n", i, ary, len(ary), cap(ary), ary)
+	}
+	/*
+	   0: 0x140000180b8 len:1 cap:1 [0]
+	   1: 0x140000180e0 len:2 cap:2 [0 1]
+	   2: 0x1400001e040 len:3 cap:4 [0 1 2]
+	   3: 0x1400001e040 len:4 cap:4 [0 1 2 3]
+	   4: 0x14000014100 len:5 cap:8 [0 1 2 3 4]
+	   5: 0x14000014100 len:6 cap:8 [0 1 2 3 4 5]
+	   6: 0x14000014100 len:7 cap:8 [0 1 2 3 4 5 6]
+	   7: 0x14000014100 len:8 cap:8 [0 1 2 3 4 5 6 7]
+	   8: 0x1400006e000 len:9 cap:16 [0 1 2 3 4 5 6 7 8]
+	   9: 0x1400006e000 len:10 cap:16 [0 1 2 3 4 5 6 7 8 9]
+	*/
+}
+
diff --git a/collection/array.go b/collection/array.go
new file mode 100644
index 0000000..9cd6461
--- /dev/null
+++ b/collection/array.go
@@ -0,0 +1,31 @@
+package main
+
+import "fmt"
+
+func main() {
+	var a[3]int // 要素の値を省略したらゼロ値
+	fmt.Printf("a: %+v\n", a) // [0, 0, 0]
+	b := [3]int{1, 2, 3}
+	fmt.Printf("b: %+v\n", b) // [1, 2, 3]
+	c := [3]int{1, 2}
+	fmt.Printf("c: %+v\n", c) // [1, 2, 0]
+	d := [3]int{2: 2}
+	fmt.Printf("d: %+v\n", d) // [0, 0, 2]
+	e := [3]int{0:1, 1: 2}
+	fmt.Printf("e: %+v\n", e) // [1, 2, 0]
+
+	// 要素が比較可能であればその配列型も比較可能
+	fmt.Printf("a==b: %v\n", a == b) // false
+	fmt.Printf("c==e: %v\n", c == e) // true
+	// f := [4]int{}
+	// fmt.Printf("a==f: %v\n", a == f) // compile error: [3]int == [4]int
+
+	hoge(a)
+	fmt.Printf("a: %+v\n", a) // [0, 0, 0]
+	// 値渡しなので安全だが性能的に非効率なことがある
+}
+
+func hoge(arg [3]int) { 
+	arg[0] = 4
+	fmt.Printf("%+v\n", arg) // [4, 0, 0]
+}
diff --git a/collection/slice.go b/collection/slice.go
new file mode 100644
index 0000000..705cb07
--- /dev/null
+++ b/collection/slice.go
@@ -0,0 +1,16 @@
+package main
+
+import "fmt"
+
+func main() {
+	s := []string{0:"", 1:"Jan", 2:"Feb", 3:"Mar", 4:"Apr", 5:"May", 6:"Jun", 7:"Jul", 8:"Aug", 9:"Sep", 10:"Oct", 11:"Nov", 12:"Dec"}
+	fmt.Printf("%d\n", len(s)) // 13(0-12)
+	fmt.Printf("%+v\n", s[2:4]) // [Feb Mar]
+	fmt.Printf("%d\n", len(s[2:4])) // 2
+	fmt.Printf("%d\n", cap(s[2:4])) // 11(2-12)
+	fmt.Printf("%+v\n", s[2:7]) // [Feb Mar Apr May Jun]
+	fmt.Printf("%d\n", len(s[2:7])) // 5
+	fmt.Printf("%d\n", cap(s[2:7])) // 11(2-12)
+	fmt.Printf("%+v\n", s[:]) // [ Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec]
+}
+