diff --git a/src/type/globals.d.ts b/src/type/globals.d.ts
index 74fa2173cd..6c761fa17f 100644
--- a/src/type/globals.d.ts
+++ b/src/type/globals.d.ts
@@ -12,4 +12,11 @@ declare global {
   interface Window {
     readonly [SandboxKey]: import("./preload").Sandbox;
   }
+
+  interface Navigator {
+    // navigator.userAgentDataを認識してくれないため
+    userAgentData: {
+      readonly platform: string;
+    };
+  }
 }
diff --git a/src/type/preload.ts b/src/type/preload.ts
index 70612bb46f..5ead93d08a 100644
--- a/src/type/preload.ts
+++ b/src/type/preload.ts
@@ -5,10 +5,26 @@ import { Result } from "@/type/result";
 
 export const isElectron = import.meta.env.VITE_TARGET === "electron";
 export const isBrowser = import.meta.env.VITE_TARGET === "browser";
-export const isMac =
-  typeof process === "undefined"
-    ? navigator.userAgent.includes("Mac")
-    : process.platform === "darwin";
+
+// electronのメイン・レンダラープロセス内、ブラウザ内どこでも使用可能なmacOS判定
+function checkIsMac(): boolean {
+  let isMac: boolean | undefined = undefined;
+  if (process?.platform) {
+    // electronのメインプロセス用
+    isMac = process.platform === "darwin";
+  } else if (navigator?.userAgentData) {
+    // electronのレンダラープロセス用、Chrome系統が実装する実験的機能
+    isMac = navigator.userAgentData.platform.toLowerCase().includes("mac");
+  } else if (navigator?.platform) {
+    // ブラウザ用、非推奨機能
+    isMac = navigator.platform.toLowerCase().includes("mac");
+  } else {
+    // ブラウザ用、不正確
+    isMac = navigator.userAgent.toLowerCase().includes("mac");
+  }
+  return isMac;
+}
+export const isMac = checkIsMac();
 
 export const engineIdSchema = z.string().brand<"EngineId">();
 export type EngineId = z.infer<typeof engineIdSchema>;