diff --git a/src/context.ts b/src/context.ts
index 7b00108..f6de514 100644
--- a/src/context.ts
+++ b/src/context.ts
@@ -27,4 +27,5 @@ export type UIContext = {
   cut: number;
   undo: number;
   redo: number;
+  paused: boolean;
 };
diff --git a/src/main.ts b/src/main.ts
index 56e30db..f9c158d 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -1,4 +1,4 @@
-import { Application, Container } from "pixi.js";
+import { Application, Container, type Ticker } from "pixi.js";
 import type { Writable } from "svelte/store";
 import type { Context, UIContext } from "./context.ts";
 import { Grid } from "./grid.ts";
@@ -11,6 +11,16 @@ export async function setup(
   stageDefinition: StageDefinition,
   uiContext: Writable<UIContext>,
 ) {
+  let paused = false;
+  uiContext.subscribe((v) => {
+    paused = v.paused;
+  });
+  const unlessPaused = (f: (ticker: Ticker) => void) => (ticker: Ticker) => {
+    if (!paused) {
+      f(ticker);
+    }
+  };
+
   function tick() {
     // highlight is re-rendered every tick
     const highlight = player.createHighlight(cx);
@@ -50,19 +60,23 @@ export async function setup(
     elapsed: 0,
     uiContext,
   };
-  app.ticker.add((ticker) => {
-    cx.elapsed += ticker.deltaTime;
-  });
+  app.ticker.add(
+    unlessPaused((ticker) => {
+      cx.elapsed += ticker.deltaTime;
+    }),
+  );
 
   const player = new Player(cx, bunnyTexture);
-  app.ticker.add((ticker) => player.tick(cx, ticker));
+  app.ticker.add(unlessPaused((ticker) => player.tick(cx, ticker)));
   app.stage.addChild(player.sprite);
 
   let cleanup: undefined | (() => void) = undefined;
-  app.ticker.add(() => {
-    if (cleanup) cleanup();
-    cleanup = tick();
-  });
+  app.ticker.add(
+    unlessPaused(() => {
+      if (cleanup) cleanup();
+      cleanup = tick();
+    }),
+  );
 
   // Append the application canvas to the document body
   el.appendChild(app.canvas);
diff --git a/src/ui-components/Ability.svelte b/src/ui-components/Ability.svelte
index 692645a..baed080 100644
--- a/src/ui-components/Ability.svelte
+++ b/src/ui-components/Ability.svelte
@@ -2,9 +2,13 @@
 import Key from "./Key.svelte";
 type Props = { name: string; key: string; num: number };
 const { name, num, key }: Props = $props();
+let isMacOS: boolean = $state(false);
+$effect(() => {
+  isMacOS = navigator.userAgent.includes("Mac OS X");
+});
 </script>
-<span style="color: {num > 0 ? "black" : "gray"}">
-  <Key {key} enabled={num > 0} />
+<span style="color: {num > 0 ? "black" : "gray"};">
+  <Key key={isMacOS ? "⌘+" + key : "Ctrl+" + key} enabled={num > 0} />
   <span style="font-size: 1.5rem;">{name}</span>
   <span style="font-size: 1.5rem;">✕</span>
   <span style="font-size: 2rem; margin-right: 1rem;">{isFinite(num) ? num : "∞"}</span>
diff --git a/src/ui-components/Game.svelte b/src/ui-components/Game.svelte
index 86e0e93..e02a10f 100644
--- a/src/ui-components/Game.svelte
+++ b/src/ui-components/Game.svelte
@@ -1,10 +1,12 @@
 <script lang="ts">
+import { goto } from "$app/navigation";
 // client-only.
 import { Block } from "@/constants.ts";
 import type { UIContext } from "@/context.ts";
 import { setup } from "@/main.ts";
 import type { StageDefinition } from "@/stages.ts";
 import Ability from "@/ui-components/Ability.svelte";
+import Key from "@/ui-components/Key.svelte";
 import { writable } from "svelte/store";
 
 type Props = { stageNum: string; stage: StageDefinition };
@@ -18,12 +20,24 @@ const uiContext = writable<UIContext>({
   paste: 0,
   undo: 0,
   redo: 0,
+  paused: false,
 });
 $effect(() => {
   if (container) {
     setup(container, stage, uiContext);
   }
 });
+
+$effect(() => {
+  const onKeyDown = (event: KeyboardEvent) => {
+    if (event.key === "Escape") {
+      event.preventDefault();
+      uiContext.update((prev) => ({ ...prev, paused: !prev.paused }));
+    }
+  };
+  document.addEventListener("keydown", onKeyDown);
+  return () => document.removeEventListener("keydown", onKeyDown);
+});
 </script>
 
 <div bind:this={container} class="container">
@@ -32,7 +46,9 @@ $effect(() => {
     style="position: fixed; left: 0; top: 0; right: 0; display: flex; align-items: baseline;"
   >
     <span style="font-size: 2rem; margin-right:0.5rem;">Stage:</span>
-    <span style="font-size: 2.5rem">{stageNum}</span>
+    <span style="font-size: 2.5rem; margin-right: 1.5rem;">{stageNum}</span>
+    <Key key="Esc" enabled />
+    <span style="font-size: 1.5rem; margin-left: 0.5rem;">to pause</span>
     <span style="flex-grow: 1"></span>
     <span style="font-size: 1.5rem;">Clipboard:</span>
     <div class="inventory">
@@ -62,6 +78,24 @@ $effect(() => {
     <Ability key="Z" name="Undo" num={$uiContext.undo} />
     <Ability key="Y" name="Redo" num={$uiContext.redo} />
   </div>
+  {#if $uiContext.paused}
+    <div class="uiBackground menu">
+      <span style="font-size: 2rem;">Paused</span>
+      <!-- todo: ボタンのスタイル -->
+      <button
+        style="font-size: 1.5rem;"
+        onclick={() => uiContext.update((prev) => ({ ...prev, paused: false }))}
+        >Resume</button
+      >
+      <button
+        style="font-size: 1.5rem;"
+        onclick={() => window.location.reload()}>Restart</button
+      >
+      <button style="font-size: 1.5rem;" onclick={() => goto("/")}
+        >Back to Stage Select</button
+      >
+    </div>
+  {/if}
 </div>
 
 <style>
@@ -85,4 +119,19 @@ $effect(() => {
     border-radius: 0.5rem;
     border-color: oklch(87.9% 0.169 91.605);
   }
+  .menu {
+    position: fixed;
+    left: 0;
+    top: 0;
+    right: 0;
+    bottom: 0;
+    display: flex;
+    flex-direction: column;
+    margin: auto;
+    align-items: center;
+    width: max-content;
+    height: max-content;
+    gap: 0.5rem;
+    border-radius: 1rem;
+  }
 </style>
diff --git a/src/ui-components/Key.svelte b/src/ui-components/Key.svelte
index 5bc33fa..0688091 100644
--- a/src/ui-components/Key.svelte
+++ b/src/ui-components/Key.svelte
@@ -1,13 +1,9 @@
 <script lang="ts">
 type Props = { key: string; enabled: boolean };
 const { key, enabled }: Props = $props();
-let isMacOS: boolean = $state(false);
-$effect(() => {
-  isMacOS = navigator.userAgent.includes("Mac OS X");
-});
 </script>
 <span class="key" style="border-color: {enabled ? "black" : "gray"}; background: {enabled ? "white" : "lightgray"};">
-  {isMacOS ? "⌘+" + key : "Ctrl+" + key}
+  {key}
 </span>
 <style>
   .key{