diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index a0dc501..de9a869 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -15,7 +15,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        java: [19]
+        java: 21
         os: ['ubuntu-latest', 'macos-latest', 'windows-latest']
     runs-on: ${{ matrix.os }}
     name: Build on ${{ matrix.os }} on Java ${{ matrix.java }}
@@ -33,7 +33,7 @@ jobs:
         run: |
           ./gradlew --no-daemon -s :build
       - name: Upload coverage to Codecov
-        if: ${{ matrix.java == '19' && matrix.os == 'ubuntu-latest' }}
+        if: ${{ matrix.java == '21' && matrix.os == 'ubuntu-latest' }}
         uses: codecov/codecov-action@v3.1.4
       - name: Save reports
         uses: actions/upload-artifact@v3
diff --git a/.github/workflows/security.yml b/.github/workflows/security.yml
index 8041db7..62639d6 100644
--- a/.github/workflows/security.yml
+++ b/.github/workflows/security.yml
@@ -15,11 +15,11 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: gradle/wrapper-validation-action@v1
-      - name: Use JDK 19
+      - name: Use JDK 21
         uses: actions/setup-java@v4
         with:
           distribution: 'temurin'
-          java-version: 19
+          java-version: 21
       - name: Initialize CodeQL
         uses: github/codeql-action/init@v2
         with:
diff --git a/build.gradle b/build.gradle
index 6c0ec5d..992bfae 100644
--- a/build.gradle
+++ b/build.gradle
@@ -368,7 +368,7 @@ javadoc {
 }
 javadoc.options {
 	addBooleanOption('-enable-preview', true)
-	addStringOption('-release', '19')
+	addStringOption('-release', '21')
 }
 
 def moduleName = "com.jyuzawa.onnxruntime"