To prevent interference of a rear end part of a baggage box 20 and a rear part bumper 26 when the rear part bumper 26 is made movable in a longitudinal direction, thereby the baggage box 20 is lifted up by attaching or turning it making a turning support part as a center.

The rear part bumper 26 is mounted to a pair of left and right arms through a mounting frame 32, and the arms 33 are slidably guided in the longitudinal direction by left and right guide cylinders 35. The guide cylinders 35 are mounted to the left and right frames through a bracket 38. The rear part bumper 26 is moved in the longitudinal direction using an expansion/contraction cylinder 41, and the rear part bumper 26 pushed out to a rear side by a claw 58 is locked by a lock cylinder 48.