diff --git a/.Lib9c.Tests/Action/ItemEnhancementTest.cs b/.Lib9c.Tests/Action/ItemEnhancementTest.cs
index d69271af8b..4e23dedd97 100644
--- a/.Lib9c.Tests/Action/ItemEnhancementTest.cs
+++ b/.Lib9c.Tests/Action/ItemEnhancementTest.cs
@@ -544,5 +544,46 @@ public void Execute_With_Hammer(bool oldStart)
             Assert.Equal(preItemUsable.ItemId, resultEquipment.ItemId);
             Assert.Equal(expectedCost, slotResult.gold);
         }
+
+        [Theory]
+        [InlineData(true)]
+        [InlineData(false)]
+        public void Execute_Throw_InvalidItemTypeException(bool withMaterials)
+        {
+            var types = ItemEnhancement.HammerBannedTypes;
+            foreach (var itemSubType in types)
+            {
+                var row =
+                    _tableSheets.EquipmentItemSheet.Values.First(r => r.ItemSubType == itemSubType);
+                var equipment = ItemFactory.CreateItemUsable(row, Guid.NewGuid(), 0);
+                _avatarState.inventory.AddItem(equipment);
+                _initialState = _initialState.SetAvatarState(_avatarAddress, _avatarState);
+                var materialIds = new List<Guid>();
+                if (withMaterials)
+                {
+                    materialIds.Add(Guid.NewGuid());
+                    materialIds.Add(Guid.NewGuid());
+                }
+
+                var action = new ItemEnhancement
+                {
+                    itemId = equipment.ItemId,
+                    materialIds = materialIds,
+                    avatarAddress = _avatarAddress,
+                    slotIndex = 0,
+                    hammers = new Dictionary<int, int>
+                    {
+                        [600301] = 3,
+                    },
+                };
+                Assert.Throws<InvalidItemTypeException>(() => action.Execute(new ActionContext
+                {
+                    BlockIndex = 1,
+                    PreviousState = _initialState,
+                    RandomSeed = 0,
+                    Signer = _agentAddress,
+                }));
+            }
+        }
     }
 }
diff --git a/Lib9c/Action/ItemEnhancement.cs b/Lib9c/Action/ItemEnhancement.cs
index a757d58560..773c4b3783 100644
--- a/Lib9c/Action/ItemEnhancement.cs
+++ b/Lib9c/Action/ItemEnhancement.cs
@@ -220,7 +220,8 @@ public override IWorld Execute(IActionContext context)
 
             // Validate enhancement materials
             var uniqueMaterialIds = materialIds.Distinct().ToList();
-            if (!uniqueMaterialIds.Any())
+            // Validate hammer without materials count
+            if (hammers.Any())
             {
                 if (HammerBannedTypes.Contains(enhancementEquipment.ItemSubType))
                 {