To improve workability in work for fixing an upper part of a damper to a car body.

A hook-like locking projection 31a is disposed in the upper part of the damper 18 and inserted into a locking hole 23c formed in the lower surface of a side frame 11, and the damper 18 is rotated to engage the locking projection 31a with the locking hole 23c, and hence the damper 18 is temporarily fixed to the car body frame 11. In this state, two bolts 40 inserted from the downside are screwed into weld nuts 25 to fix the damper 18. Thus, it is not required that one operator inserts the damper from the downside of the car body and the other operator screws the nuts from the upside of the car body to fix the damper. Therefore, one operator can mount the damper 18, and hence the workability is improved. Especially, the temporarily fixed damper 18 does not fall even if it is not held by a hand, so that screwing work of the bolts 40 into the weld nuts 25 is further facilitated.