diff --git a/frontend/src/pages/theatres/TheatreDetailPage.tsx b/frontend/src/pages/theatres/TheatreDetailPage.tsx
index 79edd41..dac7856 100644
--- a/frontend/src/pages/theatres/TheatreDetailPage.tsx
+++ b/frontend/src/pages/theatres/TheatreDetailPage.tsx
@@ -150,7 +150,7 @@ export default (() => {
     }
 
     tick ()
-    const interval = setInterval (() => tick (), 1_000)
+    const interval = setInterval (() => tick (), 5_000)
 
     return () => {
       cancelled = true
@@ -188,6 +188,9 @@ export default (() => {
   }, [id, loading, theatreInfo.hostFlg, theatreInfo.postId])
 
   useEffect (() => {
+    setPost (null)
+    setVideoLength (0)
+
     if (theatreInfo.postId == null)
       return
 
@@ -209,7 +212,7 @@ export default (() => {
     return () => {
       cancelled = true
     }
-  }, [theatreInfo.postId, theatreInfo.postStartedAt])
+  }, [theatreInfo.postId])
 
   const syncPlayback = (meta: NiconicoMetadata) => {
     if (!(theatreInfo.postStartedAt))
@@ -244,6 +247,7 @@ export default (() => {
 	  {post ? (
 	      <>
 		<PostEmbed
+		    key={post ? `${ post.id }:${ theatreInfo.postStartedAt ?? '' }` : 'empty'}
 		    ref={embedRef}
 		    post={post}
 		    onLoadComplete={info => {