diff --git a/index.html b/index.html
new file mode 100644
index 0000000..b9964b9
--- /dev/null
+++ b/index.html
@@ -0,0 +1,19 @@
+<!DOCTYPE html>
+<html lang="ja">
+<head>
+  <meta charset="UTF-8">
+  <title>ESP32 ブラウザ書き込みツール</title>
+  <script type="module" src="https://unpkg.com/esp-web-tools@9/dist/web/install-button.js?module"></script>
+  <style>
+    body { font-family: sans-serif; text-align: center; padding: 2rem; background: #f4f6f8; }
+    .card { background: white; max-width: 500px; margin: auto; padding: 2rem; border-radius: 8px; box-shadow: 0 2px 8px rgba(0,0,0,0.1); }
+  </style>
+</head>
+<body>
+  <div class="card">
+    <h2>ESP32 実機書き込み</h2>
+    <p>ChromebookとESP32をUSBケーブルで接続し、下のボタンを押してください。</p>
+    <esp-web-install-button manifest="manifest.json"></esp-web-install-button>
+  </div>
+</body>
+</html>