diff --git a/code_study/Baekjoon/java/_1991.java b/code_study/Baekjoon/java/_1991.java
new file mode 100644
index 0000000..87a8b19
--- /dev/null
+++ b/code_study/Baekjoon/java/_1991.java
@@ -0,0 +1,97 @@
+import java.util.*;
+
+class Node {
+    char value;
+    Node left;
+    Node right;
+
+    public Node(char value) {
+        this.value = value;
+        this.left = null;
+        this.right = null;
+    }
+}
+
+class Tree {
+    Node[] data;
+
+    public Tree(int N) {
+        this.data = new Node[N];
+    }
+
+    public void insertNode_byCharlist(char[] char_list) {
+        char root = char_list[0];
+        char left = char_list[1];
+        char right = char_list[2];
+
+        if(data[root-'A'] == null) {
+            data[root-'A'] = new Node(root);
+        }
+
+        if('A'<=left && left<='Z') {
+            if(data[left-'A'] == null) data[left-'A'] = new Node(left);
+            data[root-'A'].left = data[left-'A'];
+        }
+
+        if('A'<=right && right<='Z') {
+            if(data[right-'A'] == null) data[right-'A'] = new Node(right);
+            data[root-'A'].right = data[right-'A'];
+        }
+    }
+
+    public void preorder() {
+        preorder(this.data[0]);
+        System.out.println();
+    }
+
+    public void inorder() {
+        inorder(this.data[0]);
+        System.out.println();
+    }
+
+    public void postorder() {
+        postorder(this.data[0]);
+        System.out.println();
+    }
+
+    private void preorder(Node node) {
+        if (node == null) return;
+
+        System.out.print(node.value);
+        preorder(node.left);
+        preorder(node.right);
+    }
+
+    private void inorder(Node node) {
+        if (node == null) return;
+
+        inorder(node.left);
+        System.out.print(node.value);
+        inorder(node.right);
+    }
+
+    private void postorder(Node node) {
+        if (node == null) return;
+        
+        postorder(node.left);
+        postorder(node.right);
+        System.out.print(node.value);
+    }
+}
+
+public class _1991 {
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int N = Integer.parseInt(sc.nextLine());
+        Tree tree = new Tree(N);
+        for(int i=0; i<N; i++) {
+            char[] input = sc.nextLine().replace(" ", "").toCharArray();
+            tree.insertNode_byCharlist(input);
+        }
+        sc.close();
+
+        tree.preorder();
+        tree.inorder();
+        tree.postorder();
+    }
+}
\ No newline at end of file