To secure an approaching angle, absorb an impact load caused by a bumper, and provide attaching strength for a towing hook.

Side face parts 33,34 of a bumper stay 31 are coupled to a plate-like attaching stay 21 provided in an end part of a sideframe 11, the towing hook 3 in a tip of which a hook part 4 is formed to be laid longitudinally is attached, by a welding nut 37, to a bumper attaching part 32 of the bumper stay 31 coupled to a bumper beam 41, and a base end 6 of the towing hook 3 is inserted into an insertion hole 23 drilled in the attaching stay 21 with a clearance.