diff --git a/feature/wallet/src/main/java/one/nem/kidshift/wallet/HistoryItemListAdapter.java b/feature/wallet/src/main/java/one/nem/kidshift/wallet/HistoryItemListAdapter.java
index 43af539..d46fdb8 100644
--- a/feature/wallet/src/main/java/one/nem/kidshift/wallet/HistoryItemListAdapter.java
+++ b/feature/wallet/src/main/java/one/nem/kidshift/wallet/HistoryItemListAdapter.java
@@ -181,7 +181,7 @@ public class HistoryItemListAdapter extends RecyclerView.Adapter<HistoryItemList
             }
         });
         if (holder instanceof MonthHeaderViewHolder) {
-            ((MonthHeaderViewHolder) holder).monthHeaderTitle.setText(historyData.getRegisteredAt().getMonth() + "月");
+            ((MonthHeaderViewHolder) holder).monthHeaderTitle.setText(historyData.getRegisteredAt().getMonth() + 1 + "月");
 //            // DEBUG: 月をまたぐデータがないので
 //            ((MonthHeaderViewHolder) holder).monthHeaderTitle.setText(historyData.getRegisteredAt().getDate() + "日");
             ((MonthHeaderViewHolder) holder).monthTotalTextView.setText(getMonthTotal(historyData) + "円");