To prevent a vehicle body from floating up with a simple structure, and to easily assemble right and left rear suspensions on a vehicle body.

An elevating base 24 capable of placing a pair of right and left rear suspensions S is elevatably supported respectively at a supporting base 23 positioned and fixed at the lower part of a vehicle B. A chain drive means staitionaly disposed at the supporting base 23 is connected with chains 28 so as to pull the chains 28 equipped at one end with a hook 27 capable of engaging with an engaging hole 26 formed at the rear end of the vehicle body B. The movement of the chain 28 is thus prevented by a locking means 30 with the chain 28 pulled by a prescribed length with the chain drive means.