diff --git a/JavaOOP/src/Java19.java b/JavaOOP/src/Java19.java
new file mode 100644
index 00000000..d0c9db5e
--- /dev/null
+++ b/JavaOOP/src/Java19.java
@@ -0,0 +1,13 @@
+import myObject.Animal;
+import myObject.Cat;
+import myObject.Dog;
+
+public class Java19 {
+    public static void main(String[] args) {
+        Animal dog = new Dog(); // 상속 관계 : 자동 형변환 -> Object casting  부모 클래스 = 자식클래스 (Up casting)
+        Animal cat = new Cat();
+
+        dog.eat();
+        cat.eat();
+    }
+}
diff --git a/JavaOOP/src/myObject/Cat.java b/JavaOOP/src/myObject/Cat.java
index b65b0c17..b5b8f329 100644
--- a/JavaOOP/src/myObject/Cat.java
+++ b/JavaOOP/src/myObject/Cat.java
@@ -1,4 +1,8 @@
 package myObject;
 
 public class Cat extends Animal{
+    @Override
+    public void eat() {
+        System.out.println("고양이가 먹는다");
+    }
 }
diff --git a/JavaOOP/src/myObject/Dog.java b/JavaOOP/src/myObject/Dog.java
index 441ecbf5..97f6ea9d 100644
--- a/JavaOOP/src/myObject/Dog.java
+++ b/JavaOOP/src/myObject/Dog.java
@@ -1,4 +1,8 @@
 package myObject;
 
 public class Dog extends Animal{
+    @Override
+    public void eat() {
+        System.out.println("개가 먹는다");
+    }
 }