To easily arrange the hook capable of tracting heavy load even in a vehicle in a monocock structure.

The right and left rear frames 1 of a vehicle are welded to both the lower surface of a floor panel and the front surface of a rear end cross member 3, a right and a left supporting member 3 are also welded to the inner side surfaces of the right and left rear frames 1, the lower surface of the floor panel and the lower surface of the rear end cross member 2, and a mounting plate 16 is welded to the center part of a cross pipe 15 connecting the rear end parts of the right and left supporting members 3 with each other, so that a tracting hook is thereby mounted to the aforesaid mounting plate 16.