diff --git a/program/serializers.py b/program/serializers.py
index cee5711d10eca02912cad0a1ae8804fe04ce554d..28aea07e6cf4a9794cb1f7e790e8822f7e10ec5d 100644
--- a/program/serializers.py
+++ b/program/serializers.py
@@ -509,7 +509,7 @@ class CollisionSerializer(serializers.Serializer):
     playlist_id = serializers.IntegerField(allow_null=True)
     show = serializers.IntegerField()
     show_name = serializers.CharField()
-    is_repetition = serializers.BooleanField()
+    repetition_of = serializers.IntegerField(allow_null=True)
     schedule = serializers.IntegerField()
     memo = serializers.CharField()
     note_id = serializers.IntegerField(allow_null=True)
@@ -536,7 +536,7 @@ class DryRunTimeSlotSerializer(serializers.Serializer):
     playlist_id = serializers.IntegerField(allow_null=True)
     start = serializers.DateField()
     end = serializers.DateField()
-    is_repetition = serializers.BooleanField()
+    repetition_of = serializers.IntegerField(allow_null=True)
     memo = serializers.CharField()
 
 
@@ -570,6 +570,7 @@ class ScheduleDryRunResponseSerializer(serializers.Serializer):
 class TimeSlotSerializer(serializers.ModelSerializer):
     show = serializers.PrimaryKeyRelatedField(queryset=Show.objects.all())
     schedule = serializers.PrimaryKeyRelatedField(queryset=Schedule.objects.all())
+    repetition_of = serializers.PrimaryKeyRelatedField(queryset=TimeSlot.objects.all())
 
     class Meta:
         model = TimeSlot
@@ -579,7 +580,6 @@ class TimeSlotSerializer(serializers.ModelSerializer):
             "start",
             "end",
             "memo",
-            "is_repetition",
             "playlist_id",
             "note_id",
         )
@@ -593,8 +593,8 @@ class TimeSlotSerializer(serializers.ModelSerializer):
 
         # Only save certain fields
         instance.memo = validated_data.get("memo", instance.memo)
-        instance.is_repetition = validated_data.get(
-            "is_repetition", instance.is_repetition
+        instance.repetition_of = validated_data.get(
+            "repetition_of", instance.repetition_of
         )
         instance.playlist_id = validated_data.get("playlist_id", instance.playlist_id)
         instance.save()