diff --git a/src/components/Layout/layout.js b/src/components/Layout/layout.js
index 0191533..4847680 100644
--- a/src/components/Layout/layout.js
+++ b/src/components/Layout/layout.js
@@ -5,6 +5,7 @@ import Transition from '../Transition';
 import Navbar from '../Navbar';
 import Head from './Head';
 import Footer from '../Footer';
+import MigrationNotice from '../MigrationNotice';
 import './index.scss';
 
 if (typeof window !== 'undefined') {
@@ -17,6 +18,7 @@ const Layout = ({ children, location }) => (
   <div className="layout">
     <Head />
     <Navbar location={location} />
+    <MigrationNotice />
     <Transition location={location}>
       <div className="container-fluid">{children}</div>
     </Transition>
diff --git a/src/components/MigrationNotice/index.js b/src/components/MigrationNotice/index.js
new file mode 100644
index 0000000..a8f0a7e
--- /dev/null
+++ b/src/components/MigrationNotice/index.js
@@ -0,0 +1,38 @@
+import React, { useState, useEffect } from 'react';
+import './index.scss';
+
+function MigrationNotice() {
+  const [isVisible, setIsVisible] = useState(false);
+
+  useEffect(() => {
+    const hasSeenNotice = localStorage.getItem('migration-notice-seen');
+    if (!hasSeenNotice) {
+      setIsVisible(true);
+    }
+  }, []);
+
+  const handleClose = () => {
+    setIsVisible(false);
+    localStorage.setItem('migration-notice-seen', 'true');
+  };
+
+  if (!isVisible) return null;
+
+  return (
+    <div className="migration-notice">
+      <div className="migration-notice-content">
+        <span>
+          ⚠️ このブログ記事は&nbsp;
+          <a href="https://yumenomatayume.net" target="_blank" rel="noopener noreferrer">
+            yumenomatayume.net
+          </a>
+          &nbsp;のブログページへ移行しました。
+          2026/3/31 に本サイトは閉鎖し、新しいサイトにリダイレクトされます。
+        </span>
+        <button type="button" className="close-btn" onClick={handleClose}>×</button>
+      </div>
+    </div>
+  );
+}
+
+export default MigrationNotice;
diff --git a/src/components/MigrationNotice/index.scss b/src/components/MigrationNotice/index.scss
new file mode 100644
index 0000000..84a63ab
--- /dev/null
+++ b/src/components/MigrationNotice/index.scss
@@ -0,0 +1,48 @@
+.migration-notice {
+  background: #dc3545;
+  color: white;
+  padding: 0.75rem 0;
+  position: sticky;
+  top: 0;
+  z-index: 1000;
+  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
+
+  .migration-notice-content {
+    max-width: 1200px;
+    margin: 0 auto;
+    padding: 0 1rem;
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    gap: 1rem;
+
+    span {
+      flex: 1;
+      font-size: 0.9rem;
+      line-height: 1.4;
+    }
+
+    .close-btn {
+      background: none;
+      border: none;
+      color: white;
+      font-size: 18px;
+      cursor: pointer;
+      padding: 0.25rem;
+      opacity: 0.8;
+      flex-shrink: 0;
+
+      &:hover {
+        opacity: 1;
+      }
+    }
+  }
+
+  @media (max-width: 768px) {
+    .migration-notice-content {
+      span {
+        font-size: 0.85rem;
+      }
+    }
+  }
+}
