diff --git "a/\352\271\200\354\225\204\353\246\260/java-basic/src/poly/basic/Child.java" "b/\352\271\200\354\225\204\353\246\260/java-basic/src/poly/basic/Child.java"
new file mode 100644
index 0000000..cb0f055
--- /dev/null
+++ "b/\352\271\200\354\225\204\353\246\260/java-basic/src/poly/basic/Child.java"
@@ -0,0 +1,7 @@
+package poly.basic;
+
+public class Child extends Parent {
+    public void childMethod() {
+        System.out.println("Child.childMethod");
+    }
+}
diff --git "a/\352\271\200\354\225\204\353\246\260/java-basic/src/poly/basic/Parent.java" "b/\352\271\200\354\225\204\353\246\260/java-basic/src/poly/basic/Parent.java"
new file mode 100644
index 0000000..12fc6f5
--- /dev/null
+++ "b/\352\271\200\354\225\204\353\246\260/java-basic/src/poly/basic/Parent.java"
@@ -0,0 +1,7 @@
+package poly.basic;
+
+public class Parent {
+    public void parentMethod() {
+        System.out.println("Parent.parentMethod");
+    }
+}
diff --git "a/\352\271\200\354\225\204\353\246\260/java-basic/src/poly/basic/PolyMain.java" "b/\352\271\200\354\225\204\353\246\260/java-basic/src/poly/basic/PolyMain.java"
new file mode 100644
index 0000000..4163b14
--- /dev/null
+++ "b/\352\271\200\354\225\204\353\246\260/java-basic/src/poly/basic/PolyMain.java"
@@ -0,0 +1,29 @@
+package poly.basic;
+
+public class PolyMain {
+    public static void main(String[] args) {
+        // 부모 변수가 부모 인스턴스 참조
+        System.out.println("Parent -> Parent");
+        Parent parent = new Parent();
+        parent.parentMethod();
+
+        // 자식 변수가 자식 인스턴스 참조
+        System.out.println("Child -> Child");
+        Child child = new Child();
+        child.parentMethod();
+        child.childMethod();
+
+        // 부모 변수가 자식 인스턴스 참조 (다형적 참조)
+        System.out.println("Parent -> Child");
+        Parent poly = new Child();
+        // 부모 타입은 자식을 참조할 수 있다
+        poly.parentMethod();
+
+        // 자식은 부모를 담을 수 없다
+//        Child child1 = new Parent();
+        // 자식의 기능은 호출할 수 없다 -> 컴파일 오류 발생
+//        poly.childMethod();
+
+
+    }
+}