diff --git a/README.md b/README.md
index fe87334..ff821f0 100644
--- a/README.md
+++ b/README.md
@@ -49,6 +49,9 @@ LINE 推播目標支援分成兩組：
 - `LINE_TARGET_ID_PROD`: 正式環境用對話
 - `LINE_TARGET_MODE`: `local` 或 `prod`
 
+當系統偵測目前為 `local` 模式時，頁面右上角會顯示「測試環境」標籤。
+正式環境 `prod` 不會顯示這個標籤。
+
 ## 資料庫欄位
 
 - `time`: 目標日期，格式為 `YYYYMMDD`
diff --git a/src/App.css b/src/App.css
index df373b3..6b20956 100644
--- a/src/App.css
+++ b/src/App.css
@@ -29,10 +29,27 @@
 }
 
 .hero-copy {
+  position: relative;
   padding: 36px;
   background: linear-gradient(145deg, rgba(255, 247, 234, 0.92), rgba(232, 244, 235, 0.84));
 }
 
+.env-badge {
+  position: absolute;
+  top: 20px;
+  right: 20px;
+  display: inline-flex;
+  align-items: center;
+  min-height: 34px;
+  padding: 0 14px;
+  border-radius: 999px;
+  background: rgba(186, 61, 47, 0.12);
+  color: #8d2d22;
+  font-size: 0.84rem;
+  font-weight: 700;
+  letter-spacing: 0.08em;
+}
+
 .eyebrow {
   margin: 0 0 12px;
   color: #1d6c46;
@@ -371,6 +388,11 @@
     padding: 18px;
   }
 
+  .env-badge {
+    position: static;
+    margin-bottom: 14px;
+  }
+
   .team-line {
     flex-wrap: wrap;
   }
diff --git a/src/App.tsx b/src/App.tsx
index 34ad51b..6a0dfec 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -26,6 +26,10 @@ type LoadMatchResultsResponse = {
   battlecombination: string | null
 }
 
+type HealthResponse = {
+  lineTargetMode?: string
+}
+
 const STORAGE_KEYS = {
   areaA: 'badminton-match-hub::area-a',
   areaB: 'badminton-match-hub::area-b',
@@ -49,6 +53,7 @@ function App() {
   const [error, setError] = useState('')
   const [actionState, setActionState] = useState<ActionState>('idle')
   const [actionMessage, setActionMessage] = useState('')
+  const [showTestBadge, setShowTestBadge] = useState(false)
 
   useEffect(() => {
     window.localStorage.setItem(STORAGE_KEYS.areaA, areaAInput)
@@ -58,6 +63,13 @@ function App() {
     window.localStorage.setItem(STORAGE_KEYS.areaB, areaBInput)
   }, [areaBInput])
 
+  useEffect(() => {
+    void (async () => {
+      const isLocalMode = await loadEnvironmentMode()
+      setShowTestBadge(isLocalMode)
+    })()
+  }, [])
+
   const parsedAreaA = parseRoster(areaAInput)
   const parsedAreaB = parseRoster(areaBInput)
   const teamCount = Math.max(parsedAreaA.length, parsedAreaB.length)
@@ -196,6 +208,7 @@ function App() {
     <main className="app-shell">
       <section className="hero-card">
         <div className="hero-copy">
+          {showTestBadge ? <div className="env-badge">測試環境</div> : null}
           <p className="eyebrow">羽毛球隊伍配對</p>
           <h1>羽毛球分組配對器</h1>
           <p className="hero-text">
@@ -477,6 +490,20 @@ async function pushMatchResultsToLine(time: string, rounds: RoundResult[]) {
   }
 }
 
+async function loadEnvironmentMode() {
+  try {
+    const response = await fetch('/api/health')
+    if (!response.ok) {
+      return false
+    }
+
+    const payload = (await response.json()) as HealthResponse
+    return payload.lineTargetMode === 'local'
+  } catch {
+    return false
+  }
+}
+
 function convertDbRecordToAppState(record: LoadMatchResultsResponse) {
   const personnel = JSON.parse(record.personnel) as [number, string][]
   const battlecombination = JSON.parse(record.battlecombination ?? '{}') as Record<