diff --git a/workflows/u/admin/alexa_speak.script.yaml b/workflows/u/admin/alexa_speak.script.yaml
index 091b41b..fcfa041 100644
--- a/workflows/u/admin/alexa_speak.script.yaml
+++ b/workflows/u/admin/alexa_speak.script.yaml
@@ -6,10 +6,11 @@ schema:
   type: object
   properties:
     device:
-      type: string
+      type: object
       description: ''
       default: null
-      originalType: string
+      format: dynselect-device
+      originalType: DynSelect_device
     text:
       type: string
       description: ''
diff --git a/workflows/u/admin/alexa_speak.ts b/workflows/u/admin/alexa_speak.ts
index a25942c..cf6a39c 100644
--- a/workflows/u/admin/alexa_speak.ts
+++ b/workflows/u/admin/alexa_speak.ts
@@ -1,20 +1,69 @@
+/**
+ * alexa_speak.ts
+ * 指定した Echo デバイスにテキストを読み上げさせる Windmill スクリプト
+ *
+ * パラメータ:
+ *   device - ドロップダウンから選択するデバイス（内部的にはシリアル番号）
+ *   text   - 読み上げるテキスト
+ */
+
+const ALEXA_API_URL = "http://alexa_api:3500";
+
+type DeviceOption = { value: string; label: string };
+
+const FALLBACK_DEVICE_OPTIONS: DeviceOption[] = [
+  { value: "G0922H085165007R", label: "プレハブ (G0922H085165007R)" },
+  { value: "G8M2DB08522600RL", label: "リビングエコー1 (G8M2DB08522600RL)" },
+  { value: "G8M2DB08522503WF", label: "リビングエコー2 (G8M2DB08522503WF)" },
+  { value: "G0922H08525302K5", label: "オフィスの右エコー (G0922H08525302K5)" },
+  { value: "G0922H08525302J9", label: "オフィスの左エコー (G0922H08525302J9)" },
+  { value: "G8M2HN08534302XH", label: "寝室のエコー (G8M2HN08534302XH)" },
+];
+
+// Windmill Dynamic Select: 引数名 `device` に対応する `DynSelect_device` と `device()` を定義
+export type DynSelect_device = string;
+
+export async function device(): Promise<DeviceOption[]> {
+  try {
+    const res = await fetch(`${ALEXA_API_URL}/devices`);
+    if (!res.ok) return FALLBACK_DEVICE_OPTIONS;
+
+    const devices = (await res.json()) as Array<{
+      name?: string;
+      serial?: string;
+      family?: string;
+    }>;
+
+    const options = devices
+      .filter((d) => d.family === "ECHO" && d.serial)
+      .map((d) => ({
+        value: d.serial as string,
+        label: `${d.name ?? d.serial} (${d.serial})`,
+      }))
+      .sort((a, b) => a.label.localeCompare(b.label, "ja"));
+
+    return options.length > 0 ? options : FALLBACK_DEVICE_OPTIONS;
+  } catch {
+    return FALLBACK_DEVICE_OPTIONS;
+  }
+}
+
 export async function main(
-  device: string,
+  device: DynSelect_device,
   text: string,
 ): Promise<{ ok: boolean; device: string; text: string }> {
-  const ALEXA_API_URL = "http://alexa_api:3500";
-
   const res = await fetch(`${ALEXA_API_URL}/speak`, {
     method: "POST",
     headers: { "Content-Type": "application/json" },
-    body: JSON.stringify({ device, text }),  // ← SSMLなし、素のテキスト
+    body: JSON.stringify({ device, text }),
   });
 
   if (!res.ok) {
     const body = await res.json().catch(() => ({}));
-    throw new Error(`alexa-api error ${res.status}: ${JSON.stringify(body)}`);
+    throw new Error(
+      `alexa-api error ${res.status}: ${JSON.stringify(body)}`
+    );
   }
 
   return await res.json();
 }
-
diff --git a/workflows/wmill-lock.yaml b/workflows/wmill-lock.yaml
index 05d5407..3f5bb31 100644
--- a/workflows/wmill-lock.yaml
+++ b/workflows/wmill-lock.yaml
@@ -19,7 +19,7 @@ locks:
   f/weather/weather_sync__flow+気象データ取得・同期.py: 86c9953ec7346601eaa13c681e2db5c01c9a5b4b45a3c47e8667ad3c47557029
   g/all/setup_app__app+__app_hash: d71add32e14e552d1a4c861c972a50d9598b07c0af201bbadec5b59bbd99d7e3
   g/all/setup_app__app+change_account.deno.ts: 3c592cac27e9cdab0de6ae19270bcb08c7fa54355ad05253a12de2351894346b
-  u/admin/alexa_speak: 38de2eb567f82488e6f819c82dc7d83f41d83f015fac0c944d98dcc6b33a29a1
+  u/admin/alexa_speak: e5bef63ab682e903715056cf24b4a94e87a14d4db60d8d29cd7c579359b56c72
   u/admin/hub_sync: aaf9fd803fa229f3029d1bb02bbe3cc422fce680cad39c4eec8dd1da115de102
   u/akiracraftwork/hourly_chime__flow+__flow_hash: 79974bee69ff196e45a08b74e9539d8a3b50885ef0abba6907a00530809984fa
   u/akiracraftwork/hourly_chime__flow+a.ts: b27320279be1d14184a210632e15d0e89d701243545d2d73cdd20e11dd413c53