diff --git a/islands/Container.tsx b/islands/Container.tsx
index 1e6fe22..cecbf46 100644
--- a/islands/Container.tsx
+++ b/islands/Container.tsx
@@ -13,6 +13,7 @@ import { initState, set_state } from "../server/state.ts";
 import NewTask from "../components/NewTask.tsx";
 import { parse_int } from "../server/parse.ts";
 import { detect_darkmode } from "../server/dark.ts";
+import { registeServiceWorker } from "../server/sw.ts";
 
 export type ContainerProps = {
     i18n: I18NMap;
@@ -68,6 +69,12 @@ export default class Container extends Component<ContainerProps> {
             } else if (dm === DarkMode.Dark) {
                 document.body.classList.add("dark-scheme");
             }
+            registeServiceWorker("/sw.js", { updateViaCache: "all" }).catch(
+                (e) => {
+                    console.error("Failed to registe service worker.");
+                    console.error(e);
+                },
+            );
         }, []);
         return (
             <div>
diff --git a/server/sw.ts b/server/sw.ts
new file mode 100644
index 0000000..e67d3d0
--- /dev/null
+++ b/server/sw.ts
@@ -0,0 +1,10 @@
+export async function registeServiceWorker(
+    path: string,
+    options?: RegistrationOptions,
+) {
+    const r = await navigator.serviceWorker.getRegistration(path);
+    if (r === undefined) {
+        return await navigator.serviceWorker.register(path, options);
+    }
+    return r;
+}