diff --git a/lib/src/core/engine/progress_service.dart b/lib/src/core/engine/progress_service.dart
index daec89b..00047e6 100644
--- a/lib/src/core/engine/progress_service.dart
+++ b/lib/src/core/engine/progress_service.dart
@@ -17,6 +17,7 @@ import 'package:asciineverdie/src/core/model/monster_combat_stats.dart';
 import 'package:asciineverdie/src/core/model/potion.dart';
 import 'package:asciineverdie/src/core/model/pq_config.dart';
 import 'package:asciineverdie/src/core/model/skill.dart';
+import 'package:asciineverdie/src/core/util/balance_constants.dart';
 import 'package:asciineverdie/src/core/util/pq_logic.dart' as pq_logic;
 
 class ProgressTickResult {
@@ -549,10 +550,13 @@ class ProgressService {
     );
 
     // 전투용 몬스터 레벨 조정 (밸런스)
-    // config의 raw 레벨이 플레이어보다 너무 높으면 전투가 불가능
-    // 플레이어 레벨 ±3 범위로 제한 (최소 1)
+    // Act별 최소 레벨과 플레이어 레벨 중 큰 값을 기준으로 ±3 범위 제한
+    final actMinLevel = ActMonsterLevel.forPlotStage(
+      state.progress.plotStageCount,
+    );
+    final baseLevel = math.max(level, actMinLevel);
     final effectiveMonsterLevel = monsterResult.level
-        .clamp(math.max(1, level - 3), level + 3)
+        .clamp(math.max(1, baseLevel - 3), baseLevel + 3)
         .toInt();
 
     final monsterCombatStats = MonsterCombatStats.fromLevel(
@@ -849,11 +853,25 @@ class ProgressService {
   }
 
   GameState forcePlotComplete(GameState state) {
-    final progress = state.progress.copyWith(
-      task: state.progress.task.copyWith(position: state.progress.task.max),
-      plot: state.progress.plot.copyWith(position: state.progress.plot.max),
+    // 다음 Act의 최소 몬스터 레벨까지 레벨업
+    final nextPlotStage = state.progress.plotStageCount + 1;
+    final targetLevel = ActMonsterLevel.forPlotStage(nextPlotStage);
+    var nextState = state;
+
+    // 현재 레벨이 목표 레벨보다 낮으면 레벨업
+    while (nextState.traits.level < targetLevel) {
+      nextState = _levelUp(nextState);
+    }
+
+    final progress = nextState.progress.copyWith(
+      task: nextState.progress.task.copyWith(
+        position: nextState.progress.task.max,
+      ),
+      plot: nextState.progress.plot.copyWith(
+        position: nextState.progress.plot.max,
+      ),
     );
-    return state.copyWith(progress: progress);
+    return nextState.copyWith(progress: progress);
   }
 
   GameState _applyReward(GameState state, pq_logic.RewardKind reward) {
diff --git a/lib/src/core/util/balance_constants.dart b/lib/src/core/util/balance_constants.dart
index 32030ae..5a948dc 100644
--- a/lib/src/core/util/balance_constants.dart
+++ b/lib/src/core/util/balance_constants.dart
@@ -416,6 +416,40 @@ class LevelTierSettings {
   }
 }
 
+/// Act별 최소 몬스터 레벨 (act minimum monster level)
+///
+/// 플레이어 레벨과 무관하게 각 Act에서 등장하는 몬스터의 최소 레벨.
+/// 저레벨 플레이어가 고Act에 도달해도 적절한 난이도 유지.
+class ActMonsterLevel {
+  ActMonsterLevel._();
+
+  /// plotStageCount 기준 최소 몬스터 레벨
+  /// - 1: Prologue → 1
+  /// - 2: Act I → 3
+  /// - 3: Act II → 22
+  /// - 4: Act III → 45
+  /// - 5: Act IV → 72
+  /// - 6: Act V → 88
+  static const List<int> _minimumLevels = [
+    1, // index 0: unused (plotStageCount starts at 1)
+    1, // Prologue (plotStageCount = 1)
+    3, // Act I (plotStageCount = 2)
+    22, // Act II (plotStageCount = 3)
+    45, // Act III (plotStageCount = 4)
+    72, // Act IV (plotStageCount = 5)
+    88, // Act V (plotStageCount = 6)
+  ];
+
+  /// plotStageCount에 해당하는 최소 몬스터 레벨 반환
+  static int forPlotStage(int plotStageCount) {
+    if (plotStageCount < 1) return 1;
+    if (plotStageCount >= _minimumLevels.length) {
+      return _minimumLevels.last;
+    }
+    return _minimumLevels[plotStageCount];
+  }
+}
+
 /// 플레이어 스탯 스케일링 (player stat scaling)
 class PlayerScaling {
   PlayerScaling._();