PURPOSE: To facilitate loading and unloading by making a guide plate go in and out through a coupling means, interlocking it with the opening and closing operation of a trunk lid, and by forming an incline for the level difference between the floor face of a trunk room and a road face.

CONSTITUTION: At the opening on car width side of a trunk room provided under the floor of the car body of a bus is a trunk lid 3 attached to the car body side member so as to open the top side in door close position At outward with a hinge shaft Ct. Inward of the door close position At of the trunk lid 3 is a guide plate 5 attached to the member of a floor 4 so as to open the under side in the storage position Ag outward with a hinge shaft Cg. Furthermore, at both ends in the vicinity of each hinge shaft Ct and Cg is each couplig means D1 and D2 provided for interlocking the opening and closing operation of the guide plate to the opening and closing operation of the trunk lid 3. When opening or closing the trunk lid 3, an incline is made between the trunk room floor 4 and the road face with the guide plate 5.