diff --git a/Question15-Polymorphism/.gitignore b/Question15-Polymorphism/.gitignore
new file mode 100644
index 0000000..84c048a
--- /dev/null
+++ b/Question15-Polymorphism/.gitignore
@@ -0,0 +1 @@
+/build/
diff --git a/Question15-Polymorphism/src/main/java/Car.java b/Question15-Polymorphism/src/main/java/Car.java
new file mode 100644
index 0000000..23defc9
--- /dev/null
+++ b/Question15-Polymorphism/src/main/java/Car.java
@@ -0,0 +1,14 @@
+public class Car {
+	
+    protected String name;
+    protected int speed;
+
+    public Car(String name, int speed) {
+        this.name = name;
+        this.speed = speed;
+    }
+
+    public void run() {
+        System.out.println(name + "は時速" + speed + "で走った");
+    }
+}
diff --git a/Question15-Polymorphism/src/main/java/Q15_1.java b/Question15-Polymorphism/src/main/java/Q15_1.java
new file mode 100644
index 0000000..159474d
--- /dev/null
+++ b/Question15-Polymorphism/src/main/java/Q15_1.java
@@ -0,0 +1,15 @@
+
+public class Q15_1 {
+	
+    public static void main(String[] args) {
+        
+        Car car1 = new SportsCar();
+
+        car1.run();
+       
+        Car car2 = new Truck();
+
+        car2.run();
+        
+    }
+}
diff --git a/Question15-Polymorphism/src/main/java/Q15_2.java b/Question15-Polymorphism/src/main/java/Q15_2.java
new file mode 100644
index 0000000..ccf41a3
--- /dev/null
+++ b/Question15-Polymorphism/src/main/java/Q15_2.java
@@ -0,0 +1,23 @@
+import java.util.ArrayList;
+import java.util.List;
+
+public class Q15_2 {
+	
+	public static void main(String[] args) {
+		
+	        Car sportsCar = new SportsCar();
+
+	        
+	        Car truck = new Truck();
+
+	        
+	        List<Car> carList = new ArrayList<>();
+	        carList.add(sportsCar);
+	        carList.add(truck);
+
+	        
+	        for (Car car : carList) {
+	            car.run();
+	        }
+	}
+}
diff --git a/Question15-Polymorphism/src/main/java/Q15_3.java b/Question15-Polymorphism/src/main/java/Q15_3.java
new file mode 100644
index 0000000..402fb9f
--- /dev/null
+++ b/Question15-Polymorphism/src/main/java/Q15_3.java
@@ -0,0 +1,17 @@
+
+public class Q15_3 {
+
+	public static void main(String[] args) {
+		// TODO 自動生成されたメソッド・スタブ
+		
+		Car car = new SportsCar();
+
+		
+		SportsCar sportsCar = (SportsCar) car;
+
+		
+		sportsCar.turboRun(); 
+		
+	}
+
+}
diff --git a/Question15-Polymorphism/src/main/java/SportsCar.java b/Question15-Polymorphism/src/main/java/SportsCar.java
new file mode 100644
index 0000000..daee8f0
--- /dev/null
+++ b/Question15-Polymorphism/src/main/java/SportsCar.java
@@ -0,0 +1,12 @@
+
+public class SportsCar extends Car {
+	
+	    public SportsCar() {
+	        super("スポーツカー", 100);
+	    }
+
+	    public void turboRun() {
+	    	
+	        System.out.println(name + "は時速" + (speed * 3) + "で走った");
+	    }
+	}
\ No newline at end of file
diff --git a/Question15-Polymorphism/src/main/java/Truck.java b/Question15-Polymorphism/src/main/java/Truck.java
new file mode 100644
index 0000000..9bee2b6
--- /dev/null
+++ b/Question15-Polymorphism/src/main/java/Truck.java
@@ -0,0 +1,8 @@
+
+public class Truck extends Car {
+
+	
+    public Truck() {
+        super("トラック", 30);
+    }
+}