PURPOSE: To provide the installation structure of a rear bumper which can increase the rigidity of the lower end part of the rear bumper, simplify the structure of a shaping mold, improve the outside appearance.

CONSTITUTION: As for the installation structure of a rear bumper, a rib 4 which extends to the rear end part of the body is arranged over all the width on the reverse surface 3a side at the lower end part of the bumper body 3, and the rear bumper 1 is installed at the rear end part of the body by tightening- fixing the tightened part 5 of the rib 4 by a screw 7 and a welding nut 14.