diff --git a/src/face_geometry.py b/src/face_geometry.py
index 377518b..c838053 100644
--- a/src/face_geometry.py
+++ b/src/face_geometry.py
@@ -3,6 +3,7 @@
 from .config_loader import FaceSettings
 from .models import FaceROI, TrackedPerson
 
+TRUNCATED_WIDTH_RATIO = 0.8
 
 def create_face_roi(person: TrackedPerson, frame_width: int, frame_height: int, config: FaceSettings) -> FaceROI | None:
     """Create a clipped upper-body ROI or return None when the track is ineligible."""
@@ -12,12 +13,14 @@ def create_face_roi(person: TrackedPerson, frame_width: int, frame_height: int,
         return None
     bbox = person.bbox
     candidate_height = bbox.height * config.roi_height_ratio
+    if bbox.y2 >= frame_height - 2:
+        candidate_height = max(candidate_height, bbox.width * TRUNCATED_WIDTH_RATIO)
     expand_x = bbox.width * config.roi_expand_ratio
     expand_y = candidate_height * config.roi_expand_ratio
     y1 = max(0, round(bbox.y1 - expand_y))
     y2 = min(frame_height, round(bbox.y1 + candidate_height + expand_y))
     if config.roi_square:
-        half = (y2 - y1) / 2.0          # 縦幅と同じ幅の正方形
+        half = (y2 - y1) / 2.0
         x1 = max(0, round(bbox.center_x - half))
         x2 = min(frame_width, round(bbox.center_x + half))
     else: