diff --git a/app.py b/app.py
index 96172d0..a0d8e12 100644
--- a/app.py
+++ b/app.py
@@ -4,6 +4,7 @@
 """
 
 import streamlit as st
+import streamlit.components.v1 as components
 from PIL import Image
 import os
 from typing import Optional, Union
@@ -52,6 +53,58 @@
 )
 
 
+def inject_keyboard_shortcuts():
+    """
+    JavaScriptを入れて，キーボードの左右矢印キーで画面上の「◀」「▶」ボタンをプログラム的にクリックさせる
+    """
+    js_code = """
+    <script>
+    (function() {
+        const doc = window.parent.document;
+        
+        // すでにリスナーが登録されている場合は何もしない（重複防止）
+        if (window.parent._hasIVUSShortcuts) {
+            return;
+        }
+        window.parent._hasIVUSShortcuts = true;
+
+        doc.addEventListener('keydown', function(e) {
+            const active = doc.activeElement;
+            
+            // 【重要】テキスト入力中のみ除外するロジックを修正
+            // TEXTAREA は無条件で除外（コメント入力など）
+            // INPUT は type="range" (スライダー) 以外の場合のみ除外（名前入力など）
+            if (active.tagName === 'TEXTAREA') {
+                return;
+            }
+            if (active.tagName === 'INPUT' && active.type !== 'range') {
+                return;
+            }
+
+            const buttons = Array.from(doc.querySelectorAll('button'));
+
+            if (e.key === 'ArrowLeft') {
+                const prevBtn = buttons.find(b => b.innerText.includes('◀'));
+                if (prevBtn) {
+                    // ブラウザのデフォルト動作（スライダー移動など）をキャンセル
+                    e.preventDefault();
+                    e.stopPropagation();
+                    prevBtn.click();
+                }
+            } else if (e.key === 'ArrowRight') {
+                const nextBtn = buttons.find(b => b.innerText.includes('▶'));
+                if (nextBtn) {
+                    e.preventDefault();
+                    e.stopPropagation();
+                    nextBtn.click();
+                }
+            }
+        });
+    })();
+    </script>
+    """
+    components.html(js_code, height=0)
+
 def open_folder_dialog(initial_dir: str = ".") -> str:
     """
     Windows標準のフォルダ選択ダイアログを開き、選択されたパスを返す。
@@ -339,17 +392,28 @@
         st.markdown("---")
 
         # --- 画像拡大率 ---
-        st.subheader("表示設定")
-        zoom_percent = st.select_slider(
-            "画像拡大率",
-            options=[30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150],
-            value=st.session_state.zoom_percent,
-            format_func=lambda x: f"{x}%",
-            key="global_zoom"
-        )
-        if zoom_percent != st.session_state.zoom_percent:
-            st.session_state.zoom_percent = zoom_percent
-            st.rerun()
+        zoom_levels = [30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150]
+        if st.session_state.zoom_percent not in zoom_levels:
+            st.session_state.zoom_percent = 80
+        
+        current_idx = zoom_levels.index(st.session_state.zoom_percent)
+        
+        col_z1, col_z2, col_z3 = st.columns([1, 2, 1])
+        
+        with col_z1:
+            if st.button("－", key="zoom_out", use_container_width=True):
+                if current_idx > 0:
+                    st.session_state.zoom_percent = zoom_levels[current_idx - 1]
+                    st.rerun()
+                    
+        with col_z2:
+            st.markdown(f"<div style='text-align: center; line-height: 2.3;'><b>{st.session_state.zoom_percent} %</b></div>", unsafe_allow_html=True)
+            
+        with col_z3:
+            if st.button("＋", key="zoom_in", use_container_width=True):
+                if current_idx < len(zoom_levels) - 1:
+                    st.session_state.zoom_percent = zoom_levels[current_idx + 1]
+                    st.rerun()
 
 
 def render_image_viewer(case_id: Union[int, float], container):
@@ -371,19 +435,28 @@
     if frame_key not in st.session_state:
         st.session_state[frame_key] = 0
 
+    # ボタンが押されたときに実行される関数
+    def change_frame(amount: int):
+        current = st.session_state[frame_key]
+        new_val = current + amount
+        if 0 <= new_val < len(images):
+            st.session_state[frame_key] = new_val
+            # st.rerun()
+
     # Image slider
     frame_idx = container.slider(
         "フレーム番号",
         min_value=0,
         max_value=len(images) - 1,
         value=st.session_state[frame_key],
-        key=f"frame_slider_{case_id}",
-        on_change=lambda: None  # Ensure state updates
+        key=frame_key,
+        label_visibility="collapsed",
+        # on_change=lambda: None  # Ensure state updates
     )
 
     # Update session state from slider
-    if frame_idx != st.session_state[frame_key]:
-        st.session_state[frame_key] = frame_idx
+    # if frame_idx != st.session_state[frame_key]:
+    #     st.session_state[frame_key] = frame_idx
 
     # Display image with custom width based on global zoom level
     try:
@@ -403,19 +476,34 @@
         with col1:
             st.write("")  # Spacer
         with col2:
-            if st.button("◀", key=f"prev_frame_{case_id}", disabled=frame_idx == 0, use_container_width=True):
-                st.session_state[frame_key] = frame_idx - 1
-                st.rerun()
+            st.button(
+                "◀",
+                key=f"prev_{case_id}",
+                on_click=change_frame,
+                args=(-1,),
+            )
+            # if st.button("◀", key=f"prev_{case_id}"):
+            #     if frame_idx > 0:
+            #         st.session_state[frame_key] = frame_idx - 1
+            #         st.rerun()
         with col3:
-            if st.button("▶", key=f"next_frame_{case_id}", disabled=frame_idx >= len(images) - 1, use_container_width=True):
-                st.session_state[frame_key] = frame_idx + 1
-                st.rerun()
+            st.button(
+                "▶",
+                key=f"next_{case_id}",
+                on_click=change_frame,
+                args=(1,),
+            )
+            # if st.button("▶", key=f"next_{case_id}", disabled=frame_idx >= len(images) - 1):
+            #     if frame_idx < len(images) - 1:
+            #         st.session_state[frame_key] = frame_idx + 1
+            #         st.rerun()
 
     except Exception as e:
         container.error(f"画像読み込みエラー: {e}")
 
     # Keyboard navigation support (キーボードの矢印キーでフレーム移動)
     container.caption("💡 ヒント: スライダーをクリックしてから矢印キー(←→)でフレーム移動、または◀▶ボタンをクリックできます")
+    inject_keyboard_shortcuts()
 
 
 def render_annotation_form(container, case_id: Union[int, float]) -> dict: