diff --git a/app.js b/app.js
index 5b239dd..885a2b7 100644
--- a/app.js
+++ b/app.js
@@ -1,11 +1,21 @@
 'use strict';
 const fs = require('fs');
 const fileName = './test.txt';
-for (let count = 0; count < 500; count++) {
-  fs.appendFile(fileName, 'あ', 'utf8', () => {});
-  fs.appendFile(fileName, 'い', 'utf8', () => {});
-  fs.appendFile(fileName, 'う', 'utf8', () => {});
-  fs.appendFile(fileName, 'え', 'utf8', () => {});
-  fs.appendFile(fileName, 'お', 'utf8', () => {});
-  fs.appendFile(fileName, '\n', 'utf8', () => {});
-}
\ No newline at end of file
+
+function appendFilePromise(fileName, str) {
+  return new Promise((resolve) => {
+    fs.appendFile(fileName, str, 'utf8', () => resolve());
+  });
+}
+async function main() {
+  for (let count = 0; count < 500; count++) {
+    await appendFilePromise(fileName, 'あ');
+    await appendFilePromise(fileName, 'い');
+    await appendFilePromise(fileName, 'う');
+    await appendFilePromise(fileName, 'え');
+    await appendFilePromise(fileName, 'お');
+    await appendFilePromise(fileName, '\n');
+  }
+}
+
+main();
diff --git a/async-test.js b/async-test.js
new file mode 100644
index 0000000..e84d8fe
--- /dev/null
+++ b/async-test.js
@@ -0,0 +1,8 @@
+'use strict'
+const fs = require('fs');
+const fileName = './test.txt';
+for (let count = 0; count < 30; count++) {
+  fs.appendFileSync(fileName, 'おはようございます\n', 'utf8');
+  fs.appendFileSync(fileName, 'こんにちは\n', 'utf8');
+  fs.appendFileSync(fileName, 'こんばんは\n', 'utf8' );
+}
\ No newline at end of file
diff --git a/promise-test.js b/promise-test.js
new file mode 100644
index 0000000..bbf5b65
--- /dev/null
+++ b/promise-test.js
@@ -0,0 +1,27 @@
+'use strict'
+
+new Promise((resolve) => {
+    const nowDate = new Date();
+    resolve(nowDate);
+  })
+    .then((v1) => {
+      // v1 は 現在の時刻情報
+      const monthAndDate = {
+        month: v1.getMonth(),
+        date: v1.getDate()
+      }
+      return new Promise((resolve) => {
+        resolve(monthAndDate);
+      });
+    })
+    .then((v2) => {
+      // v2 は 日付の情報
+      const text = `今日は${v2.month+1}月${v2.date}日です。`;
+      return new Promise((resolve) => {
+        resolve(text);
+      });
+    })
+    .then((v3) => {
+      // v3 は 日付を示す文章
+      console.log(v3); // 今日の日付に関する文章が出力される
+    });
\ No newline at end of file