diff --git a/app/build.gradle b/app/build.gradle
index 01cbefe..2f46e19 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -20,6 +20,9 @@
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
         }
     }
+    sourceSets{
+        main.java.srcDirs += 'src/main/kotlin'
+    }
 }
 
 dependencies {
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 3edad43..2fdefc4 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -9,7 +9,8 @@
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/AppTheme">
-        <activity android:name=".MainActivity">
+        <activity android:name=".KotlinMainActivity"></activity>
+        <activity android:name=".JavaMainActivity">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
 
diff --git a/app/src/main/java/org/ntlab/developrx/JavaMainActivity.java b/app/src/main/java/org/ntlab/developrx/JavaMainActivity.java
new file mode 100644
index 0000000..fd67971
--- /dev/null
+++ b/app/src/main/java/org/ntlab/developrx/JavaMainActivity.java
@@ -0,0 +1,16 @@
+package org.ntlab.developrx;
+
+import android.os.Bundle;
+import android.support.v7.app.AppCompatActivity;
+
+/**
+ * Created by matsumoto_k on 2017/11/11.
+ */
+public class JavaMainActivity extends AppCompatActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_main_java);
+    }
+}
diff --git a/app/src/main/java/org/ntlab/developrx/MainActivity.kt b/app/src/main/java/org/ntlab/developrx/MainActivity.kt
deleted file mode 100644
index e24ef69..0000000
--- a/app/src/main/java/org/ntlab/developrx/MainActivity.kt
+++ /dev/null
@@ -1,12 +0,0 @@
-package org.ntlab.developrx
-
-import android.support.v7.app.AppCompatActivity
-import android.os.Bundle
-
-class MainActivity : AppCompatActivity() {
-
-    override fun onCreate(savedInstanceState: Bundle?) {
-        super.onCreate(savedInstanceState)
-        setContentView(R.layout.activity_main)
-    }
-}
diff --git a/app/src/main/kotlin/org/ntlab/developrx/KotlinMainActivity.kt b/app/src/main/kotlin/org/ntlab/developrx/KotlinMainActivity.kt
new file mode 100644
index 0000000..2db650f
--- /dev/null
+++ b/app/src/main/kotlin/org/ntlab/developrx/KotlinMainActivity.kt
@@ -0,0 +1,15 @@
+package org.ntlab.developrx
+
+import android.os.Bundle
+import android.support.v7.app.AppCompatActivity
+
+/**
+ * Created by matsumoto_k on 2017/11/11.
+ */
+class KotlinMainActivity : AppCompatActivity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_main_kotlin)
+    }
+}
diff --git a/app/src/main/res/layout/activity_main.xml b/app/src/main/res/layout/activity_main.xml
deleted file mode 100644
index e363d4e..0000000
--- a/app/src/main/res/layout/activity_main.xml
+++ /dev/null
@@ -1,18 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
-    xmlns:tools="http://schemas.android.com/tools"
-    android:layout_width="match_parent"
-    android:layout_height="match_parent"
-    tools:context="org.ntlab.developrx.MainActivity">
-
-    <TextView
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:text="Hello World!"
-        app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintLeft_toLeftOf="parent"
-        app:layout_constraintRight_toRightOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
-
-</android.support.constraint.ConstraintLayout>
diff --git a/app/src/main/res/layout/activity_main_java.xml b/app/src/main/res/layout/activity_main_java.xml
new file mode 100644
index 0000000..bbce02c
--- /dev/null
+++ b/app/src/main/res/layout/activity_main_java.xml
@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context="org.ntlab.developrx.JavaMainActivity">
+
+    <TextView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Hello World!"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintLeft_toLeftOf="parent"
+        app:layout_constraintRight_toRightOf="parent"
+        app:layout_constraintTop_toTopOf="parent" />
+
+</android.support.constraint.ConstraintLayout>
diff --git a/app/src/main/res/layout/activity_main_kotlin.xml b/app/src/main/res/layout/activity_main_kotlin.xml
new file mode 100644
index 0000000..d81ae37
--- /dev/null
+++ b/app/src/main/res/layout/activity_main_kotlin.xml
@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context="org.ntlab.developrx.KotlinMainActivity">
+
+    <TextView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Hello World!"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintLeft_toLeftOf="parent"
+        app:layout_constraintRight_toRightOf="parent"
+        app:layout_constraintTop_toTopOf="parent" />
+
+</android.support.constraint.ConstraintLayout>