diff --git a/action.yml b/action.yml
index 32cdec7..a4789be 100644
--- a/action.yml
+++ b/action.yml
@@ -69,17 +69,50 @@ runs:
         sudo apt-get update
         sudo apt-get install -y --no-install-recommends fonts-noto-cjk
 
+    # browser-actions/setup-chrome は RUNNER_TOOL_CACHE 配下にキャッシュする作りだが、
+    # GitHub-hosted runner は毎回使い捨て VM なのでジョブをまたいでは残らない。
+    # actions/cache で永続化し、2回目以降のダウンロードをスキップする。
+    - name: Restore Chrome for Testing cache
+      id: chrome-cache
+      uses: actions/cache/restore@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
+      with:
+        path: ${{ runner.tool_cache }}/setup-chrome
+        key: chromagic-chrome-${{ runner.os }}-${{ runner.arch }}
+
     - name: Setup Chrome for Testing
       id: chrome
       uses: browser-actions/setup-chrome@2e1d749697dd1612b833dba4a722266286fbefcd # v2
       with:
         install-dependencies: true
 
+    - name: Save Chrome for Testing cache
+      if: ${{ steps.chrome-cache.outputs.cache-hit != 'true' }}
+      uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
+      with:
+        path: ${{ runner.tool_cache }}/setup-chrome
+        key: ${{ steps.chrome-cache.outputs.cache-primary-key }}
+
+    # action 自体の node_modules(storycap 等)も package-lock.json のハッシュでキャッシュする。
+    - name: Restore action dependencies cache
+      id: deps-cache
+      uses: actions/cache/restore@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
+      with:
+        path: ${{ github.action_path }}/node_modules
+        key: chromagic-deps-${{ runner.os }}-${{ hashFiles(format('{0}/package-lock.json', github.action_path)) }}
+
     - name: Install action dependencies
+      if: ${{ steps.deps-cache.outputs.cache-hit != 'true' }}
       shell: bash
       # consumer 側は実行に要る依存だけ(devDeps=semantic-release 等は入れない)。
       run: npm ci --prefix "$GITHUB_ACTION_PATH" --omit=dev --no-audit --no-fund
 
+    - name: Save action dependencies cache
+      if: ${{ steps.deps-cache.outputs.cache-hit != 'true' }}
+      uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
+      with:
+        path: ${{ github.action_path }}/node_modules
+        key: ${{ steps.deps-cache.outputs.cache-primary-key }}
+
     - name: Capture stories (storycap)
       shell: bash
       # inputs は run ブロックへ直接展開せず env 経由で渡す(shell/式インジェクション対策)。