diff --git a/Assets/Scripts/Mechanics/PlayerController.cs b/Assets/Scripts/Mechanics/PlayerController.cs
index bbe07a5..93041fa 100644
--- a/Assets/Scripts/Mechanics/PlayerController.cs
+++ b/Assets/Scripts/Mechanics/PlayerController.cs
@@ -203,9 +203,19 @@ namespace Platformer.Mechanics
         void UpdateContactFilterForDropThrough()
         {
             int baseMask = Physics2D.GetLayerCollisionMask(gameObject.layer);
-            // BT41 — jumpState == Jumping 영역 영역 ascending true (PrepareToJump frame 직후 velocity.y 미반영 영역도 통과)
-            bool ascending = velocity.y > 0.01f || jumpState == JumpState.Jumping;
-            int mask = ascending ? (baseMask & ~(1 << JUMP_THROUGH_LAYER)) : baseMask;
+
+            // BT5-Dev #42 — PD 의도: 발판 위 착지(서있는) 영역만 충돌 ON, 걷기·점프·측면 영역 모두 통과
+            bool standingOnPlatform = false;
+            if (collider2d != null && IsGrounded)
+            {
+                Vector2 footPos = new Vector2(collider2d.bounds.center.x, collider2d.bounds.min.y + 0.02f);
+                int jumpThroughMask = 1 << JUMP_THROUGH_LAYER;
+                RaycastHit2D footHit = Physics2D.Raycast(footPos, Vector2.down, 0.1f, jumpThroughMask);
+                standingOnPlatform = footHit.collider != null;
+            }
+
+            // standingOnPlatform=true → Layer 16 ON (착지·서있는 영역 영역 X) / 그 외 → Layer 16 OFF (통과)
+            int mask = standingOnPlatform ? baseMask : (baseMask & ~(1 << JUMP_THROUGH_LAYER));
             contactFilter.SetLayerMask(mask);
             contactFilter.useLayerMask = true;
         }