diff --git a/src/game/mouse/space_invaders/alien.js b/src/game/mouse/space_invaders/alien.js
new file mode 100644
index 0000000..3d127a2
--- /dev/null
+++ b/src/game/mouse/space_invaders/alien.js
@@ -0,0 +1,91 @@
+class Alien extends Phaser.Sprite {
+
+	constructor(initialX, initialY, onFiredFunction, onEscapedFunction) {
+		super();
+
+		this.isActivated = false;
+		this.speedGrowing = Alien.DEFAULT_SPEED_SEC;
+		this.tweenScale = null;
+
+		this.initialX = initialX;
+		this.initialY = initialY;
+
+		this.onFiredFunction = onFiredFunction;
+		this.onEscapedFunction = onEscapedFunction;
+
+		Phaser.Sprite.call(this, game, this.initialX, this.initialY, 'alien_normal');
+		this.anchor.set(0.5);
+		this.scale.set(Alien.MAX_SCALE);
+
+		this.inputEnabled = true;
+		this.events.onInputOut.add(this.onOut, this);
+		this.events.onInputOver.add(this.onOver, this);
+		this.events.onInputDown.add(this.onDown, this);
+
+		game.add.existing(this);
+	}
+
+	onOut() {
+		if(!this.isActivated)
+			return;
+
+		// console.log("onOut");
+	}
+
+	onOver() {
+		if(!this.isActivated)
+			return;
+
+		// console.log("onOver");
+	}
+
+	onDown() {
+		if(!this.isActivated)
+			return;
+
+		// console.log("onDown");
+
+		if(this.onFiredFunction)
+			this.onFiredFunction(this);
+	}
+
+
+	setActive(isActivated) {
+		let beforeState = this.isActivated;
+		this.isActivated = isActivated;
+
+		if(beforeState && !this.isActivated) {
+			this.shutdown();
+		}
+	}
+
+	shutdown() {
+		if(!this.tweenScale) {
+			this.tweenScale.stop();
+		}
+
+		this.scale.set(0);
+	}
+
+	setOnInitialPosition() {
+		this.x = this.initialX;
+		this.y = this.initialY;
+		this.scale.set(Alien.MAX_SCALE);
+	}
+
+	moveOnStage() {
+		let SPAWN_BOX_LEFT		= 100;
+		let SPAWN_BOX_WIDTH		= game.world.width - 200;
+		let SPAWN_BOX_TOP		= 300;
+		let SPAWN_BOX_HEIGHT	= game.world.height - 400;
+
+		this.x = SPAWN_BOX_LEFT + Math.random() * SPAWN_BOX_WIDTH;
+		this.y = SPAWN_BOX_TOP + Math.random() * SPAWN_BOX_HEIGHT;
+	}
+
+}
+
+
+Alien.DEFAULT_SPEED_SEC		= 1000;
+Alien.MAX_SCALE				= 3;
+
diff --git a/src/game/mouse/space_invaders/game.js b/src/game/mouse/space_invaders/game.js
index 46ed3ae..d40dea8 100644
--- a/src/game/mouse/space_invaders/game.js
+++ b/src/game/mouse/space_invaders/game.js
@@ -19,6 +19,13 @@ class Game {
 
 
 		// contents
+		let alien = new Alien(
+			this.game.world.width / 2, this.game.world.height / 2,
+			this.onAlienFired, this.onAlienEscaped
+		);
+		alien.setActive(true);
+		alien.moveOnStage();
+		/*
 		let alien = game.add.sprite(this.game.world.width / 2, this.game.world.height / 2, 'alien_normal');
 		alien.anchor.set(0.5);
 		alien.scale.set(0);
@@ -28,6 +35,8 @@ class Game {
 		// alienTween.yoyo(true, 3000);
 		alienTween.to( { x: 4, y: 4 }, 1000, Phaser.Easing.Linear.None, false);
 		alienTween.start();
+		*/
+
 
 		// bottom
 		let screenBottom = new ScreenBottom(game);
@@ -76,4 +85,13 @@ class Game {
 		console.log("startGame");
 	}
 
+	onAlienFired(sprite) {
+		console.log("onAlienFired");
+		sprite.moveOnStage();
+	}
+
+	onAlienEscaped(sprite) {
+		console.log("onAlienEscaped");
+	}
+
 }
\ No newline at end of file
diff --git a/src/web/client/space_invaders.html b/src/web/client/space_invaders.html
index 1bce0ce..e3ddedf 100644
--- a/src/web/client/space_invaders.html
+++ b/src/web/client/space_invaders.html
@@ -26,6 +26,7 @@
 		<!-- Space Invaders : source files -->
 		<script src="../../game/mouse/space_invaders/define_variables.js"></script>
 		<script src="../../game/mouse/space_invaders/loading.js"></script>
+		<script src="../../game/mouse/space_invaders/alien.js"></script>
 		<script src="../../game/mouse/space_invaders/game.js"></script>
 		<script src="../../game/mouse/space_invaders/main.js"></script>