diff --git a/bemani/backend/sdvx/gravitywars.py b/bemani/backend/sdvx/gravitywars.py
index 99476ea..6dcb20e 100644
--- a/bemani/backend/sdvx/gravitywars.py
+++ b/bemani/backend/sdvx/gravitywars.py
@@ -501,6 +501,11 @@ class SoundVoltexGravityWars(
             achievement_rate = request.child_value('ar')
             season_id = request.child_value('ssnid')
 
+            # Do not update the course achievement when old achievement rate is greater.
+            old = self.data.local.user.get_achievement(self.game, self.version, userid, (season_id * 100) + course_id, 'course')
+            if old is not None and old.get_int('achievement_rate') > achievement_rate:
+                return Node.void('game_3')
+
             self.data.local.user.put_achievement(
                 self.game,
                 self.version,
diff --git a/bemani/backend/sdvx/heavenlyhaven.py b/bemani/backend/sdvx/heavenlyhaven.py
index 3ab3e9a..ba5db04 100644
--- a/bemani/backend/sdvx/heavenlyhaven.py
+++ b/bemani/backend/sdvx/heavenlyhaven.py
@@ -3818,6 +3818,11 @@ class SoundVoltexHeavenlyHaven(
             grade = request.child_value('gr')
             score = request.child_value('sc')
 
+            # Do not update the course achievement when old score is greater.
+            old = self.data.local.user.get_achievement(self.game, self.version, userid, (season_id * 100) + course_id, 'course')
+            if old is not None and old.get_int('score') > score:
+                return Node.void('game')
+
             self.data.local.user.put_achievement(
                 self.game,
                 self.version,
diff --git a/bemani/backend/sdvx/infiniteinfection.py b/bemani/backend/sdvx/infiniteinfection.py
index 953c125..ece96b0 100644
--- a/bemani/backend/sdvx/infiniteinfection.py
+++ b/bemani/backend/sdvx/infiniteinfection.py
@@ -2195,6 +2195,11 @@ class SoundVoltexInfiniteInfection(
             achievement_rate = request.child_value('ar')
             season_id = request.child_value('ssnid')
 
+            # Do not update the course achievement when old achievement rate is greater.
+            old = self.data.local.user.get_achievement(self.game, self.version, userid, (season_id * 100) + course_id, 'course')
+            if old is not None and old.get_int('achievement_rate') > achievement_rate:
+                return Node.void('game_2')
+
             self.data.local.user.put_achievement(
                 self.game,
                 self.version,