diff --git a/app.py b/app.py
index a0d8e12..65c2d13 100644
--- a/app.py
+++ b/app.py
@@ -366,6 +366,10 @@
             f"症例 {cid}" + (" ✓" if cid in st.session_state.annotated_cases else "")
             for cid in st.session_state.case_ids
         ]
+
+        # 症例選択のコールバック
+        def on_case_change():
+            pass
         
         selected_idx = st.selectbox(
             "症例リスト",
@@ -379,15 +383,29 @@
             st.session_state.current_case_idx = selected_idx
             st.rerun()
 
+        # 前後の症例移動ボタンのコールバック
+        def change_case(amount: int):
+            new_idx = st.session_state.current_case_idx + amount
+            if 0 <= new_idx < len(st.session_state.case_ids):
+                st.session_state.current_case_idx = new_idx
+
         col1, col2 = st.columns(2)
         with col1:
-            if st.button("← 前へ", disabled=st.session_state.current_case_idx == 0, use_container_width=True):
-                st.session_state.current_case_idx -= 1
-                st.rerun()
+            st.button(
+                "← 前へ",
+                disabled=st.session_state.current_case_idx == 0,
+                use_container_width=True,
+                on_click=change_case,
+                args=(-1,)
+            )
         with col2:
-            if st.button("次へ →", disabled=st.session_state.current_case_idx >= len(st.session_state.case_ids) - 1, use_container_width=True):
-                st.session_state.current_case_idx += 1
-                st.rerun()
+            st.button(
+                "次へ →",
+                disabled=st.session_state.current_case_idx >= len(st.session_state.case_ids) - 1,
+                use_container_width=True,
+                on_click=change_case,
+                args=(1,)
+            )
         
         st.markdown("---")
 
@@ -545,7 +563,7 @@
         "Q4: 自由記述",
         value="",
         key=f"comment_{case_id}",
-        height=68,  # 変更: 高さを約2行分に縮小
+        height=120,
         label_visibility="collapsed"
     )