diff --git a/src/modules/timer/index.ts b/src/modules/timer/index.ts
index 602ec95..3125d7e 100644
--- a/src/modules/timer/index.ts
+++ b/src/modules/timer/index.ts
@@ -24,25 +24,30 @@ export default class TimerModule implements IModule {
 			if ((seconds + minutes + hours) == 0) {
 				msg.reply(serifs.timer.invalid);
 				return true;
-			} else {
-				msg.reply(serifs.timer.set);
+			}
 
-				const time =
-					(1000 * seconds) +
-					(1000 * 60 * minutes) +
-					(1000 * 60 * 60 * hours);
-
-				const str = `${hours ? hoursQuery[0] : ''}${minutes ? minutesQuery[0] : ''}${seconds ? secondsQuery[0] : ''}`;
-
-				setTimeout(() => {
-					const name = msg.friend.name;
-					this.ai.sendMessage(msg.userId, {
-						text: serifs.timer.notify(str, name)
-					});
-				}, time);
+			const time =
+				(1000 * seconds) +
+				(1000 * 60 * minutes) +
+				(1000 * 60 * 60 * hours);
 
+			if (time > 86400000) {
+				msg.reply(serifs.timer.tooLong);
 				return true;
 			}
+
+			msg.reply(serifs.timer.set);
+
+			const str = `${hours ? hoursQuery[0] : ''}${minutes ? minutesQuery[0] : ''}${seconds ? secondsQuery[0] : ''}`;
+
+			setTimeout(() => {
+				const name = msg.friend.name;
+				this.ai.sendMessage(msg.userId, {
+					text: serifs.timer.notify(str, name)
+				});
+			}, time);
+
+			return true;
 		} else {
 			return false;
 		}
diff --git a/src/serifs.ts b/src/serifs.ts
index f7f7ae4..35269e2 100644
--- a/src/serifs.ts
+++ b/src/serifs.ts
@@ -217,6 +217,8 @@ export default {
 
 		invalid: 'うーん...？',
 
+		tooLong: '長すぎます…',
+
 		notify: (time, name) => name ? `${name}、${time}経ちましたよ！` : `${time}経ちましたよ！`
 	}
 };