diff --git a/jungmyunggi/5.js b/jungmyunggi/5.js
new file mode 100644
index 0000000..3ad95c7
--- /dev/null
+++ b/jungmyunggi/5.js
@@ -0,0 +1,28 @@
+/**
+ * @param {string} s
+ * @return {string}
+ */
+var longestPalindrome = function (s) {
+    function helper(s, left, right) {
+        while (left >= 0 && right < s.length && s[left] === s[right]) {
+            left--;
+            right++;
+        }
+        return [left, right];
+    }
+    let answer = [0, 0];
+    for (let i = 0; i < s.length; i++) {
+        const temp1 = helper(s, i, i);
+        const temp2 = helper(s, i, i + 1);
+        let result = [];
+        if (temp1[1] - temp1[0] > temp2[1] - temp2[0]) {
+            result = temp1;
+        } else {
+            result = temp2;
+        }
+
+        if (result[1] - result[0] > answer[1] - answer[0]) answer = result;
+    }
+
+    return s.slice(answer[0] + 1, answer[1]);
+};