diff --git a/app/src/main/java/jp/juggler/subwaytooter/table/NotificationShown.kt b/app/src/main/java/jp/juggler/subwaytooter/table/NotificationShown.kt
index d8de4277..26a1371a 100644
--- a/app/src/main/java/jp/juggler/subwaytooter/table/NotificationShown.kt
+++ b/app/src/main/java/jp/juggler/subwaytooter/table/NotificationShown.kt
@@ -77,10 +77,11 @@ class NotificationShown(
                     if (size <= keep * 2) continue
                     // アカウントごとに3回の削除を一度に行い、残りは次回以降にすませる
                     var deleteCount = 0
-                    while (deleteCount++ < 3) {
+                    while (size > keep && deleteCount++ < 3) {
                         // 一度に削除したい数
                         val step = min(1000, size - keep)
                         if (step <= 0) break
+
                         // 古いものからstep件目の時刻を読む
                         val time = db.rawQuery(
                             "select $COL_TIME_CREATE from $table where $COL_ACCT=? order by $COL_TIME_CREATE asc limit ?",