diff --git a/app/[docs_id]/dynamicMdContext.tsx b/app/[docs_id]/dynamicMdContext.tsx
new file mode 100644
index 0000000..779ff4e
--- /dev/null
+++ b/app/[docs_id]/dynamicMdContext.tsx
@@ -0,0 +1,40 @@
+"use client";
+
+import { createContext, ReactNode, useContext, useState } from "react";
+import { DynamicMarkdownSection } from "./pageContent";
+
+export interface ISidebarMdContext {
+  sidebarMdContent: DynamicMarkdownSection[];
+  setSidebarMdContent: React.Dispatch<React.SetStateAction<DynamicMarkdownSection[]>>;
+}
+
+const SidebarMdContext = createContext<ISidebarMdContext | null>(null);
+
+export function useSidebarMdContext() {
+  const context = useContext(SidebarMdContext);
+  if (!context) {
+    throw new Error(
+      "useSidebarMdContext must be used within a SidebarMdProvider"
+    );
+  }
+  return context;
+}
+
+export function useSidebarMdContextOptional() {
+  return useContext(SidebarMdContext);
+}
+
+export function SidebarMdProvider({
+  children,
+}: {
+  children: ReactNode;
+}) {
+  const [sidebarMdContent, setSidebarMdContent] =
+    useState<DynamicMarkdownSection[]>([]);
+
+  return (
+    <SidebarMdContext.Provider value={{ sidebarMdContent, setSidebarMdContent }}>
+      {children}
+    </SidebarMdContext.Provider>
+  );
+}
diff --git a/app/[docs_id]/pageContent.tsx b/app/[docs_id]/pageContent.tsx
index 56cc6f6..418a518 100644
--- a/app/[docs_id]/pageContent.tsx
+++ b/app/[docs_id]/pageContent.tsx
@@ -5,6 +5,7 @@ import { MarkdownSection } from "./splitMarkdown";
 import { ChatForm } from "./chatForm";
 import { Heading, StyledMarkdown } from "./markdown";
 import { useChatHistoryContext } from "./chatHistory";
+import { useSidebarMdContext } from "./dynamicMdContext";
 import clsx from "clsx";
 
 // MarkdownSectionに追加で、ユーザーが今そのセクションを読んでいるかどうか、などの動的な情報を持たせる
@@ -19,26 +20,34 @@ interface PageContentProps {
   docs_id: string;
 }
 export function PageContent(props: PageContentProps) {
+  const { setSidebarMdContent } = useSidebarMdContext();
+  
+  // SSR用のローカルstate
   const [dynamicMdContent, setDynamicMdContent] = useState<
     DynamicMarkdownSection[]
   >(
-    // useEffectで更新するのとは別に、SSRのための初期値
     props.splitMdContent.map((section, i) => ({
       ...section,
       inView: false,
       sectionId: `${props.docs_id}-${i}`,
     }))
   );
+
   useEffect(() => {
-    // props.splitMdContentが変わったときにdynamicMdContentを更新
-    setDynamicMdContent(
-      props.splitMdContent.map((section, i) => ({
-        ...section,
-        inView: false,
-        sectionId: `${props.docs_id}-${i}`,
-      }))
-    );
-  }, [props.splitMdContent, props.docs_id]);
+    // props.splitMdContentが変わったときにローカルstateとcontextの両方を更新
+    const newContent = props.splitMdContent.map((section, i) => ({
+      ...section,
+      inView: false,
+      sectionId: `${props.docs_id}-${i}`,
+    }));
+    setDynamicMdContent(newContent);
+    setSidebarMdContent(newContent);
+    
+    // クリーンアップ：コンポーネントがアンマウントされたらcontextをクリア
+    return () => {
+      setSidebarMdContent([]);
+    };
+  }, [props.splitMdContent, props.docs_id, setSidebarMdContent]);
 
   const sectionRefs = useRef<Array<HTMLDivElement | null>>([]);
   // sectionRefsの長さをsplitMdContentに合わせる
@@ -48,7 +57,7 @@ export function PageContent(props: PageContentProps) {
 
   useEffect(() => {
     const handleScroll = () => {
-      setDynamicMdContent((prevDynamicMdContent) => {
+      const updateContent = (prevDynamicMdContent: DynamicMarkdownSection[]) => {
         const dynMdContent = prevDynamicMdContent.slice(); // Reactの変更検知のために新しい配列を作成
         for (let i = 0; i < sectionRefs.current.length; i++) {
           if (sectionRefs.current.at(i) && dynMdContent.at(i)) {
@@ -58,14 +67,18 @@ export function PageContent(props: PageContentProps) {
           }
         }
         return dynMdContent;
-      });
+      };
+      
+      // ローカルstateとcontextの両方を更新
+      setDynamicMdContent(updateContent);
+      setSidebarMdContent(updateContent);
     };
     window.addEventListener("scroll", handleScroll);
     handleScroll();
     return () => {
       window.removeEventListener("scroll", handleScroll);
     };
-  }, []);
+  }, [setSidebarMdContent]);
 
   const [isFormVisible, setIsFormVisible] = useState(false);
 
diff --git a/app/layout.tsx b/app/layout.tsx
index 2589c54..59d2049 100644
--- a/app/layout.tsx
+++ b/app/layout.tsx
@@ -9,6 +9,7 @@ import { PyodideProvider } from "./terminal/python/pyodide";
 import { WandboxProvider } from "./terminal/wandbox/wandbox";
 import { EmbedContextProvider } from "./terminal/embedContext";
 import { AutoAnonymousLogin } from "./accountMenu";
+import { SidebarMdProvider } from "./[docs_id]/dynamicMdContext";
 
 export const metadata: Metadata = {
   title: "Create Next App",
@@ -22,25 +23,27 @@ export default function RootLayout({
     <html lang="ja">
       <body className="w-screen h-screen">
         <AutoAnonymousLogin />
-        <div className="drawer lg:drawer-open">
-          <input id="drawer-toggle" type="checkbox" className="drawer-toggle" />
-          <div className="drawer-content flex flex-col">
-            <Navbar />
-            <EmbedContextProvider>
-              <PyodideProvider>
-                <WandboxProvider>{children}</WandboxProvider>
-              </PyodideProvider>
-            </EmbedContextProvider>
+        <SidebarMdProvider>
+          <div className="drawer lg:drawer-open">
+            <input id="drawer-toggle" type="checkbox" className="drawer-toggle" />
+            <div className="drawer-content flex flex-col">
+              <Navbar />
+              <EmbedContextProvider>
+                <PyodideProvider>
+                  <WandboxProvider>{children}</WandboxProvider>
+                </PyodideProvider>
+              </EmbedContextProvider>
+            </div>
+            <div className="drawer-side shadow-md z-50">
+              <label
+                htmlFor="drawer-toggle"
+                aria-label="close sidebar"
+                className="drawer-overlay"
+              />
+              <Sidebar />
+            </div>
           </div>
-          <div className="drawer-side shadow-md z-50">
-            <label
-              htmlFor="drawer-toggle"
-              aria-label="close sidebar"
-              className="drawer-overlay"
-            />
-            <Sidebar />
-          </div>
-        </div>
+        </SidebarMdProvider>
       </body>
     </html>
   );
diff --git a/app/sidebar.tsx b/app/sidebar.tsx
index 1afa75b..b95fda3 100644
--- a/app/sidebar.tsx
+++ b/app/sidebar.tsx
@@ -1,23 +1,20 @@
 "use client";
 import Link from "next/link";
 import { usePathname } from "next/navigation";
-import useSWR, { Fetcher } from "swr";
-import { splitMarkdown } from "./[docs_id]/splitMarkdown";
 import { pagesList } from "./pagesList";
 import { AccountMenu } from "./accountMenu";
 import { ThemeToggle } from "./[docs_id]/themeToggle";
-
-const fetcher: Fetcher<string, string> = (url) =>
-  fetch(url).then((r) => r.text());
+import { useSidebarMdContext } from "./[docs_id]/dynamicMdContext";
 
 export function Sidebar() {
   const pathname = usePathname();
   const docs_id = pathname.replace(/^\//, "");
-  const { data, error, isLoading } = useSWR(`/docs/${docs_id}.md`, fetcher);
-
-  if (error) console.error("Sidebar fetch error:", error);
-
-  const splitmdcontent = splitMarkdown(data ?? "");
+  const { sidebarMdContent } = useSidebarMdContext();
+  
+  // 現在表示中のセクション（最初にinViewがtrueのもの）を見つける
+  const currentSectionIndex = sidebarMdContent.findIndex(
+    (section) => section.inView
+  );
   return (
     <div className="bg-base-200 h-full w-80 overflow-y-auto">
       {/* todo: 背景色ほんとにこれでいい？ */}
@@ -65,16 +62,25 @@ export function Sidebar() {
                       <span className="mr-0">{page.id}.</span>
                       {page.title}
                     </Link>
-                    {`${group.id}-${page.id}` === docs_id && !isLoading && (
+                    {`${group.id}-${page.id}` === docs_id && sidebarMdContent.length > 0 && (
                       <ul className="ml-4 text-sm">
-                        {splitmdcontent.slice(1).map((section, idx) => (
-                          <li
-                            key={idx}
-                            style={{ marginLeft: section.level - 2 + "em" }}
-                          >
-                            <Link href={`#${idx + 1}`}>{section.title}</Link>
-                          </li>
-                        ))}
+                        {sidebarMdContent.slice(1).map((section, idx) => {
+                          // idx + 1 は実際のsectionIndexに対応（slice(1)で最初を除外しているため）
+                          const isCurrentSection = idx + 1 === currentSectionIndex;
+                          return (
+                            <li
+                              key={idx}
+                              style={{ marginLeft: section.level - 2 + "em" }}
+                            >
+                              <Link
+                                href={`#${idx + 1}`}
+                                className={isCurrentSection ? "font-bold" : ""}
+                              >
+                                {section.title}
+                              </Link>
+                            </li>
+                          );
+                        })}
                       </ul>
                     )}
                   </li>