diff --git a/src/web/admin/admin_register_list.html b/src/web/admin/admin_register_list.html
index ff3ccdf..08aa4c6 100644
--- a/src/web/admin/admin_register_list.html
+++ b/src/web/admin/admin_register_list.html
@@ -25,11 +25,11 @@
 			let maestroName = $("#search_name").val();
 
 			if(maestroName.length === 0) {
-				// $("#search_name_notice").val("학생 이름을 입력하세요.");
+				$("#error_message").text("학생 이름을 입력하세요.");
 				$("#search_name").focus();
 			}
 
-			loadMaestroList($maestroName);
+			loadMaestroList(maestroName);
 		}
 
 		function loadMaestroList($maestroName) {
@@ -43,6 +43,7 @@
 					// console.log(xhr.responseText.length);
 					if(xhr.responseText.length === 0 || xhr.responseText === null) {
 						console.log("no data from server");
+						$("#error_message").text("서버에서 요청을 수행하지 못했습니다.");
 						return;
 					}
 
@@ -51,16 +52,19 @@
 
 					if(replyJSON === null) {
 						console.log("no data from server");
+						$("#error_message").text("서버에서 데이터가 넘어오지 않았습니다.");
 						return;
 					}
 
 					if(replyJSON["ERROR"] !== undefined || replyJSON["RESULT"] === undefined) {
 						console.log(replyJSON["ERROR"]);
+						$("#error_message").text(replyJSON["ERROR"]);
 						return;
 					}
 
 					if(replyJSON["RESULT"] === "fail") {
 						console.log(replyJSON["RESULT"]);
+						$("#error_message").text(replyJSON["ERROR"]);
 						return;
 					}
 
@@ -138,6 +142,7 @@
 					// console.log(xhr.responseText.length);
 					if(xhr.responseText.length === 0 || xhr.responseText === null) {
 						console.log("no data from server");
+						$("#error_message").text("서버에서 요청을 수행하지 못했습니다.");
 						return;
 					}
 
@@ -146,20 +151,24 @@
 
 					if(replyJSON === null) {
 						console.log("no data from server");
+						$("#error_message").text("서버에서 데이터가 넘어오지 않았습니다.");
 						return;
 					}
 
 					if(replyJSON["ERROR"] !== undefined || replyJSON["RESULT"] === undefined) {
 						console.log(replyJSON["ERROR"]);
+						$("#error_message").text(replyJSON["ERROR"]);
 						return;
 					}
 
 					if(replyJSON["RESULT"] === "fail") {
 						console.log(replyJSON["RESULT"]);
+						$("#error_message").text(replyJSON["ERROR"]);
 						return;
 					}
 
 					loadMaestroList("");
+					$("#error_message").text("마에스트로 계정이 정상적으로 등록되었습니다.");
 				}
 			}
 		}
@@ -177,19 +186,24 @@
 		</header>
 
 		<section id="section">
-			<span id="search_maestro_name">
-				<h1>검색</h1>
+			<div id="error_message">
+			</div>
 
-				마에스트로 이름
-				<input type="text" id="search_name"><input type="submit" name="찾기" onClick="searchMaestro()"><br/>
-				<br/>
-			</span>
+			<div>
+				<span id="search_maestro_name">
+					<h1>검색</h1>
 
-			<span id="search_result">
-				검색 결과
-				<div id="maestro_list_result_contents">
-				</div>
-			</span>
+					마에스트로 이름
+					<input type="text" id="search_name"><input type="submit" name="찾기" onClick="searchMaestro()"><br/>
+					<br/>
+				</span>
+
+				<span id="search_result">
+					검색 결과
+					<div id="maestro_list_result_contents">
+					</div>
+				</span>
+			</div>
 		</section>
 
 	</div>
diff --git a/src/web/admin/login.html b/src/web/admin/login.html
index f833daf..5562e99 100644
--- a/src/web/admin/login.html
+++ b/src/web/admin/login.html
@@ -10,6 +10,7 @@
 
 	<script type="text/javascript" src="./../../../resources/jquery/jquery-3.3.1.min.js"></script>
 	<script type="text/javascript" src="./../js/main.js"></script>
+	<script type="text/javascript" src="./../js/request_server.js"></script>
 	<script type="text/javascript">
 		$(document).ready(function() {
 			sessionStorage.setItem("maestroID", -1);
@@ -21,30 +22,25 @@
 			let name = $("#maestro_name").val();
 			let password = $("#password").val();
 
-			let xhr = new XMLHttpRequest(); //new로 생성.
-			xhr.open('POST', './../server/maestro/login.php', true);
-			xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
-			xhr.send("maestro_name=" + name + "&password=" + password);
-			xhr.onload = function() {
-				if(xhr.readyState === 4 && xhr.status === 200) {
-					let replyJSON = JSON.parse(xhr.responseText);
-					// console.log(replyJSON);
 
-					// if(replyJSON !== null)
-					// 	console.log(replyJSON);
+			sendRequestServer(	//url, sendParams, onSuccess, onFail, isDebugMode);
+				"./../server/maestro/login.php",
+				"maestro_name=" + name + "&password=" + password,
 
-					// if(replyJSON["MaestroID"] !== undefined)
-					// 	console.log(replyJSON["MaestroID"]);
+				(jsonData) => {
+					maestroID = jsonData["MaestroID"];
+					sessionStorage.setItem("maestroID", maestroID);
+					location.href = 'admin_register_list.html';
+				},
 
-					if(replyJSON !== null && replyJSON["MaestroID"] !== undefined && replyJSON["MaestroID"] !== null) {
-						maestroID = replyJSON["MaestroID"];
-						sessionStorage.setItem("maestroID", maestroID);
-						location.href = 'admin_register_list.html';
-					} else {
-						$("#error_message").val(replyJSON["ERROR"]);
+				(errorMessage) => {
+					if($("#error_message").length) {
+						$("#error_message").text(errorMessage);
 					}
 				}
-			}
+
+			);
+
 		}
 	</script>
 
@@ -54,17 +50,19 @@
 
 <body bgcolor="white">
 
-		<div>
-			관리자 아이디
-			<input type="text" id="maestro_name" name="maestro_name"><br/>
-			암호
-			<input type="password" id="password" name="password"><br/>
-		</div>
+	<div>
+		관리자 아이디
+		<input type="text" id="maestro_name" name="maestro_name"><br/>
+		암호
+		<input type="password" id="password" name="password"><br/>
+	</div>
 
-		<div class="col alignCenter">
-			<a id="login" class="btn btn-sea width400" onClick="login()">로그인</a>
-		</div>
+	<div class="col alignCenter">
+		<a id="login" class="btn btn-sea width400" onClick="login()">로그인</a>
+	</div>
 
+	<div id="error_message">
+	</div>
 
 </body>
 
diff --git a/src/web/js/main.js b/src/web/js/main.js
index 530790c..fd8ee27 100644
--- a/src/web/js/main.js
+++ b/src/web/js/main.js
@@ -33,5 +33,4 @@ function logout() {
 	maestroID = -1;
 	sessionStorage.setItem("maestroID", maestroID);
 	location.href = './../main/index.html';
-}
-
+}
\ No newline at end of file
diff --git a/src/web/js/request_server.js b/src/web/js/request_server.js
new file mode 100644
index 0000000..21cb1e8
--- /dev/null
+++ b/src/web/js/request_server.js
@@ -0,0 +1,63 @@
+function sendRequestServer(url, sendParams, onSuccess, onFail, isDebugMode) {
+	// console.log(url);
+	// console.log(sendParams);
+	// console.log(onSuccess);
+	// console.log(onFail);
+	// console.log(isDebugMode);
+
+	let xhr = new XMLHttpRequest(); //new로 생성.
+	xhr.open('POST', url, true);
+	xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
+	xhr.send(sendParams);
+	xhr.onload = function() {
+		if(xhr.readyState === 4 && xhr.status === 200) {
+			// console.log(xhr.responseText);
+			// console.log(xhr.responseText.length);
+
+			if(xhr.responseText.length === 0 || xhr.responseText === null) {
+				let error_message = "서버에서 요청을 수행하지 못했습니다.";
+				printErrorMessage(error_message, onFail, isDebugMode);
+				return;
+			}
+
+			let jsonReply = JSON.parse(xhr.responseText);
+			// console.log(jsonReply);
+
+			if(jsonReply === null) {
+				let error_message = "서버에서 데이터가 넘어오지 않았습니다.";
+				printErrorMessage(error_message, onFail, isDebugMode);
+				return;
+			}
+
+			if(!isSuccess(jsonReply)) {
+				let error_message = getErrorMessage(jsonReply);
+				printErrorMessage(error_message, onFail, isDebugMode);
+				return;
+			}
+
+			onSuccess(jsonReply);
+		}
+	}
+}
+
+function isSuccess(jsonReply) {
+	if(jsonReply["result"] === undefined)
+		return false;
+
+	if(jsonReply["result"] === "fail")
+		return false;
+
+	return true;
+}
+
+function getErrorMessage(jsonReply) {
+	return jsonReply["error"];
+}
+
+function printErrorMessage(message, onFail, isDebugMode) {
+	if(onFail !== undefined && onFail !== null)
+		onFail(message);
+
+	if(isDebugMode === true)
+		console.log(message);
+}
\ No newline at end of file
diff --git a/src/web/server/lib/send_error_code.php b/src/web/server/lib/send_error_code.php
deleted file mode 100644
index d3eeb28..0000000
--- a/src/web/server/lib/send_error_code.php
+++ /dev/null
@@ -1,10 +0,0 @@
-<?php
-
-function send_error_code($error_code) {
-    $returnValue = array(
-        'error' => $error_code
-    );
-    echo json_encode($returnValue, JSON_UNESCAPED_UNICODE);
-}
-
-?>
\ No newline at end of file
diff --git a/src/web/server/lib/send_reply_json.php b/src/web/server/lib/send_reply_json.php
new file mode 100644
index 0000000..a0339bc
--- /dev/null
+++ b/src/web/server/lib/send_reply_json.php
@@ -0,0 +1,35 @@
+<?php
+
+$jsonReply = null;
+
+function set_error_message($message) {
+	global $jsonReply;
+
+	$jsonReply["error"] = $message;
+}
+
+function set_data($name, $data) {
+	global $jsonReply;
+
+	$jsonReply[$name] = $data;
+}
+
+function send_result_success() {
+	global $jsonReply;
+	global $db_conn;
+
+	$jsonReply["result"] = "success";
+	echo json_encode($jsonReply, JSON_UNESCAPED_UNICODE);
+	$db_conn->close();
+}
+
+function send_result_fail() {
+	global $jsonReply;
+	global $db_conn;
+
+	$jsonReply["result"] = "fail";
+	echo json_encode($jsonReply, JSON_UNESCAPED_UNICODE);
+	$db_conn->close();
+}
+
+?>
\ No newline at end of file
diff --git a/src/web/server/maestro/login.php b/src/web/server/maestro/login.php
index e3a4995..786f919 100644
--- a/src/web/server/maestro/login.php
+++ b/src/web/server/maestro/login.php
@@ -1,9 +1,11 @@
 <?php
 header('Content-Type: application/json');
 
+include "./../lib/send_reply_json.php";
+include "./../setup/connect_db.php";
+
 $maestro_name = $_POST["maestro_name"];
 $password = $_POST["password"];
-
 /*
 if(!is_numeric($enterCode)) {
     send_error_code('생년월일이 숫자가 아닙니다. : '.$enterCode);
@@ -14,28 +16,26 @@ if(!is_numeric($enterCode)) {
 }
 */
 
-include "./../setup/connect_db.php";
-
 $maestro_id = get_maestro_id($maestro_name);
 if($maestro_id === null) {
-	$replyJSON["ERROR"] = "마에스트로 아이디가 없습니다";
-	echo json_encode($replyJSON, JSON_UNESCAPED_UNICODE);
-	$db_conn->close();
+	set_error_message("등록되지 않은 마에스트로 아이디입니다.");
+	send_result_fail();
 	exit;
 }
 
-$replyJSON = login($maestro_name, $password);
-if($replyJSON === null || $replyJSON[MaestroID] === null) {
-	$replyJSON["ERROR"] = "비밀번호를 잘못 입력하셨습니다.";
-	echo json_encode($replyJSON, JSON_UNESCAPED_UNICODE);
-	$db_conn->close();
+$login_data = login($maestro_name, $password);
+if($login_data === null || $login_data[maestroID] === null) {
+	set_error_message("비밀번호가 틀렸습니다.");
+	send_result_fail();
 	exit;
 }
 
-echo json_encode($replyJSON, JSON_UNESCAPED_UNICODE);
-$db_conn->close();
+set_data("maestroId", $login_data[maestroID]);
+send_result_success();
 exit;
 
+
+
 function get_maestro_id($maestro_name) {
 	global $db_conn;
 
@@ -65,8 +65,8 @@ function login($maestro_name, $password) {
 	$stmt->fetch();
 	$stmt->close();
 
-	$replyJSON["MaestroID"] = $maestro_id;
-	return $replyJSON;
+	$result["maestroID"] = $maestro_id;
+	return $result;
 }
 
 ?>
\ No newline at end of file
diff --git a/src/web/server/setup/connect_db.php b/src/web/server/setup/connect_db.php
index ab1374d..fd45821 100644
--- a/src/web/server/setup/connect_db.php
+++ b/src/web/server/setup/connect_db.php
@@ -1,7 +1,7 @@
 <?php
 
+// load service db setting
 $hasServiceDBSetting = file_exists("./../setup/service_db_setting.php");
-
 if($hasServiceDBSetting == true) {
 	include("./../setup/service_db_setting.php");
 } else {
@@ -11,27 +11,16 @@ if($hasServiceDBSetting == true) {
 	$db_name = "jisangs";
 }
 
+
+// connect db
 $db_conn = new mysqli($db_host, $db_user, $db_passwd, $db_name);
-
 if ($db_conn->connect_error) {
-    send_error_code("Connection failed: ".$db_conn->connect_error);
+    set_error_message("Failed to connect DB: ".$db_conn->connect_error);
+    send_result_fail();
     exit;
-}
-
-$query = "USE jisangs";
-$result = mysqli_query($db_conn, $query);
-
-
-function send_error_message($replyJSON, $error_message) {
-	$replyJSON["ERROR"] = $error_message;
-	echo json_encode($replyJSON, JSON_UNESCAPED_UNICODE);
-	// $db_conn->close();
-}
-
-function send_result_message($replyJSON, $result_message) {
-	$replyJSON["RESULT"] = $result_message;
-	echo json_encode($replyJSON, JSON_UNESCAPED_UNICODE);
-	// $db_conn->close();
+} else {
+	$query = "USE jisangs";
+	$result = mysqli_query($db_conn, $query);
 }
 
 ?>
\ No newline at end of file