diff --git a/src/web/js/lib/maestro_info.js b/src/web/js/lib/maestro_info.js
index 1e798cf..1c854aa 100644
--- a/src/web/js/lib/maestro_info.js
+++ b/src/web/js/lib/maestro_info.js
@@ -42,6 +42,15 @@ class MaestroInfo {
 
 			case 3:
 			return 100;
+
+			case 4:
+			return 500;
+
+			case 5:
+			return 1000;
+
+			default:
+			return 0;
 		}
 	}
 
diff --git a/src/web/module/maestro_upgrade.html b/src/web/module/maestro_upgrade.html
index a3b7f8a..1dbed53 100644
--- a/src/web/module/maestro_upgrade.html
+++ b/src/web/module/maestro_upgrade.html
@@ -97,6 +97,21 @@ function updateCards(accountType) {
 		$("#account_type_3_footer").text("현재 적용된 요금제입니다.");
 		break;
 
+		case 4:
+		case 5:
+		default:
+		$("#account_type_1_btn").addClass("btn-secondary disabled");
+		$("#account_type_1_footer").addClass("text-muted");
+		$("#account_type_1_footer").text("낮은 요금제로 내릴 수는 없습니다.");
+
+		$("#account_type_2_btn").addClass("btn-secondary disabled");
+		$("#account_type_2_footer").addClass("text-muted");
+		$("#account_type_2_footer").text("낮은 요금제로 내릴 수는 없습니다.");
+
+		$("#account_type_3_btn").addClass("btn-secondary disabled");
+		$("#account_type_3_footer").addClass("text-muted");
+		$("#account_type_3_footer").text("낮은 요금제로 내릴 수는 없습니다.");
+		break;
 
 	}
 }
diff --git a/src/web/server/player/registered_player_count.php b/src/web/server/player/registered_player_count.php
index e4b0e9b..1e11ca5 100644
--- a/src/web/server/player/registered_player_count.php
+++ b/src/web/server/player/registered_player_count.php
@@ -8,7 +8,7 @@ $maestroID = $_POST["maestro_id"];
 
 
 $playerCount = getPlayerCount($maestroID);
-if($result === null) {
+if($playerCount === null || $playerCount === 0) {
 	set_error_message("등록된 학생이 없습니다.");
 	send_result_fail();
 	exit;