diff --git a/constants/api.ts b/constants/api.ts
index 37e3861..12ff59c 100644
--- a/constants/api.ts
+++ b/constants/api.ts
@@ -7,6 +7,9 @@ const BASE_URL = 'https://jr-shikoku-api-data-storage.haruk.in';
 export const API_ENDPOINTS = {
   /** 本日のダイアグラムデータ */
   DIAGRAM_TODAY: `${BASE_URL}/tmp/diagram-today.json`,
+
+  /** 本日のダイアグラムデータ（experimental環境用） */
+  DIAGRAM_TODAY_BETA: `${BASE_URL}/tmp/diagram-today-beta.json`,
   
   /** カスタム列車データ */
   CUSTOM_TRAIN_DATA: 'https://haruk.in/api/jr/getTrain.php',
diff --git a/lib/jrDataSystemEnvironment.ts b/lib/jrDataSystemEnvironment.ts
index b7fb29f..2174aa8 100644
--- a/lib/jrDataSystemEnvironment.ts
+++ b/lib/jrDataSystemEnvironment.ts
@@ -90,6 +90,13 @@ export const getBackendApiBaseUrl = (environment: unknown): string => {
   return JR_DATA_SYSTEM_ENVS[envKey].backendApiBaseUrl;
 };
 
+export const getDiagramTodayUrl = (environment: unknown): string => {
+  const envKey = normalizeJrDataSystemEnvironment(environment);
+  return JR_DATA_SYSTEM_ENVS[envKey].track === "experimental"
+    ? "https://jr-shikoku-api-data-storage.haruk.in/tmp/diagram-today-beta.json"
+    : "https://jr-shikoku-api-data-storage.haruk.in/tmp/diagram-today.json";
+};
+
 export const rewriteBackendApiUrl = (url: string, environment: unknown): string => {
   if (typeof url !== "string" || url.length === 0) return url;
   const target = getBackendApiBaseUrl(environment);
diff --git a/lib/webViewInjectjavascript.ts b/lib/webViewInjectjavascript.ts
index 908f20f..7252521 100644
--- a/lib/webViewInjectjavascript.ts
+++ b/lib/webViewInjectjavascript.ts
@@ -41,6 +41,11 @@ export interface InjectJavascriptOptions {
    * experimental 環境では https://jr-shikoku-backend-api-v1-beta.haruk.in を渡す。
    */
   backendApiBaseUrl?: string;
+  /**
+   * ダイアグラムJSONのURL。省略時は本番URL。
+   * experimental 環境では diagram-today-beta.json のURLを渡す。
+   */
+  diagramTodayUrl?: string;
 }
 
 const PRODUCTION_BACKEND_BASE = 'https://jr-shikoku-backend-api-v1.haruk.in';
@@ -55,6 +60,7 @@ export const injectJavascriptData = ({
   useElesite,
   isDark,
   backendApiBaseUrl,
+  diagramTodayUrl,
   mockApiConfig,
 }: InjectJavascriptOptions): string => {
   const elesiteStationSequences = [
@@ -1506,6 +1512,11 @@ setStationMenuDialog.observe(document.querySelector('#disp'), {
     result = result.split(PRODUCTION_BACKEND_BASE).join(backendApiBaseUrl);
   }
 
+  const PRODUCTION_DIAGRAM_TODAY = API_ENDPOINTS.DIAGRAM_TODAY;
+  if (diagramTodayUrl && diagramTodayUrl !== PRODUCTION_DIAGRAM_TODAY) {
+    result = result.split(PRODUCTION_DIAGRAM_TODAY).join(diagramTodayUrl);
+  }
+
   // Prepend XHR interceptor as a fallback for platforms where
   // injectedJavaScriptBeforeContentLoaded doesn't run reliably.
   // The __jrsMockActive guard in the interceptor prevents double-patching
diff --git a/stateBox/useAllTrainDiagram.tsx b/stateBox/useAllTrainDiagram.tsx
index 2ca3b0c..40eef1e 100644
--- a/stateBox/useAllTrainDiagram.tsx
+++ b/stateBox/useAllTrainDiagram.tsx
@@ -12,6 +12,7 @@ import React, {
 import { API_ENDPOINTS, STORAGE_KEYS } from "@/constants";
 import {
   getBackendApiBaseUrl,
+  getDiagramTodayUrl,
   BACKEND_API_BASE_URLS,
 } from "@/lib/jrDataSystemEnvironment";
 const initialState = {
@@ -53,17 +54,23 @@ export const AllTrainDiagramProvider: FC<Props> = ({ children }) => {
   const [backendApiBaseUrl, setBackendApiBaseUrl] = React.useState(
     BACKEND_API_BASE_URLS.production,
   );
+  const [diagramTodayUrl, setDiagramTodayUrl] = React.useState(
+    "https://jr-shikoku-api-data-storage.haruk.in/tmp/diagram-today.json",
+  );
 
   React.useEffect(() => {
     AS.getItem(STORAGE_KEYS.JR_DATA_SYSTEM_ENV)
-      .then((value) => setBackendApiBaseUrl(getBackendApiBaseUrl(value)))
+      .then((value) => {
+        setBackendApiBaseUrl(getBackendApiBaseUrl(value));
+        setDiagramTodayUrl(getDiagramTodayUrl(value));
+      })
       .catch(() => {});
   }, []);
 
   const getTrainDiagram = () => {
     const controller = new AbortController();
     const timeoutId = setTimeout(() => controller.abort(), 15000);
-    fetch("https://jr-shikoku-api-data-storage.haruk.in/tmp/diagram-today.json", { signal: controller.signal })
+    fetch(diagramTodayUrl, { signal: controller.signal })
       .then((res) => res.json())
       .then((res) => {
         const data = {};
diff --git a/stateBox/useTrainMenu.tsx b/stateBox/useTrainMenu.tsx
index 84969f9..d15d463 100644
--- a/stateBox/useTrainMenu.tsx
+++ b/stateBox/useTrainMenu.tsx
@@ -39,6 +39,7 @@ import { useThemeColors } from "@/lib/theme";
 import { STORAGE_KEYS } from "@/constants/storage";
 import {
   getBackendApiBaseUrl,
+  getDiagramTodayUrl,
   BACKEND_API_BASE_URLS,
 } from "@/lib/jrDataSystemEnvironment";
 
@@ -132,6 +133,9 @@ export const TrainMenuProvider: FC<props> = ({ children }) => {
   const [backendApiBaseUrl, setBackendApiBaseUrl] = useState(
     BACKEND_API_BASE_URLS.production,
   );
+  const [diagramTodayUrl, setDiagramTodayUrl] = useState(
+    "https://jr-shikoku-api-data-storage.haruk.in/tmp/diagram-today.json",
+  );
 
   //更新権限所有確認・情報ソース別利用権限（将来ロールが増えたらここに足す）
   const [updatePermission, setUpdatePermission] = useState(false);
@@ -320,6 +324,7 @@ export const TrainMenuProvider: FC<props> = ({ children }) => {
     useElesite: useEleSiteSetting,
     isDark: useThemeColors().isDark,
     backendApiBaseUrl,
+    diagramTodayUrl,
     mockApiConfig,
   });
 
@@ -388,6 +393,7 @@ export const TrainMenuProvider: FC<props> = ({ children }) => {
     // バックエンドAPIベースURL（環境設定から読み込み）
     AS.getItem(STORAGE_KEYS.JR_DATA_SYSTEM_ENV).then((value) => {
       setBackendApiBaseUrl(getBackendApiBaseUrl(value));
+      setDiagramTodayUrl(getDiagramTodayUrl(value));
     }).catch(() => {});
     // 静的サンプルデータで初期化（モックAPIが応答するまでのフォールバック）
     setMockTrainPositions(MOCK_TRAIN_POSITIONS);