diff --git a/.github/workflows/test-backend.yml b/.github/workflows/test-backend.yml
index 9d611c9964..0c40f2c52a 100644
--- a/.github/workflows/test-backend.yml
+++ b/.github/workflows/test-backend.yml
@@ -18,6 +18,14 @@ on:
       - packages/misskey-js/**
       - .github/workflows/test-backend.yml
       - .github/misskey/test.yml
+  workflow_dispatch:
+    inputs:
+      force_ffmpeg_cache_update:
+        description: 'Force update ffmpeg cache'
+        required: false
+        default: false
+        type: boolean
+
 jobs:
   unit:
     name: Unit tests (backend)
@@ -47,7 +55,22 @@ jobs:
         submodules: true
     - name: Setup pnpm
       uses: pnpm/action-setup@v4.1.0
+    - name: Get current date
+      id: current-date
+      run: echo "today=$(date +'%Y-%m-%d')" >> $GITHUB_OUTPUT
+    - name: Setup and Restore ffmpeg/ffprobe Cache
+      id: cache-ffmpeg
+      uses: actions/cache@v4
+      with:
+        path: |
+          /usr/local/bin/ffmpeg
+          /usr/local/bin/ffprobe
+        # daily cache
+        key: ${{ runner.os }}-ffmpeg-${{ steps.current-date.outputs.today }}
+        restore-keys: |
+          ${{ runner.os }}-ffmpeg-${{ steps.current-date.outputs.today }}
     - name: Install FFmpeg
+      if: steps.cache-ffmpeg.outputs.cache-hit != 'true' || github.event.inputs.force_ffmpeg_cache_update == true
       run: |
         for i in {1..3}; do
           echo "Attempt $i: Installing FFmpeg..."
diff --git a/.github/workflows/test-federation.yml b/.github/workflows/test-federation.yml
index 737b543a73..873396f622 100644
--- a/.github/workflows/test-federation.yml
+++ b/.github/workflows/test-federation.yml
@@ -14,6 +14,13 @@ on:
       - packages/backend/**
       - packages/misskey-js/**
       - .github/workflows/test-federation.yml
+  workflow_dispatch:
+    inputs:
+      force_ffmpeg_cache_update:
+        description: 'Force update ffmpeg cache'
+        required: false
+        default: false
+        type: boolean
 
 jobs:
   test:
@@ -30,7 +37,22 @@ jobs:
           submodules: true
       - name: Setup pnpm
         uses: pnpm/action-setup@v4.1.0
+      - name: Get current date
+        id: current-date
+        run: echo "today=$(date +'%Y-%m-%d')" >> $GITHUB_OUTPUT
+      - name: Setup and Restore ffmpeg/ffprobe Cache
+        id: cache-ffmpeg
+        uses: actions/cache@v4
+        with:
+          path: |
+            /usr/local/bin/ffmpeg
+            /usr/local/bin/ffprobe
+          # daily cache
+          key: ${{ runner.os }}-ffmpeg-${{ steps.current-date.outputs.today }}
+          restore-keys: |
+            ${{ runner.os }}-ffmpeg-${{ steps.current-date.outputs.today }}
       - name: Install FFmpeg
+        if: steps.cache-ffmpeg.outputs.cache-hit != 'true' || github.event.inputs.force_ffmpeg_cache_update == true
         run: |
           for i in {1..3}; do
             echo "Attempt $i: Installing FFmpeg..."