A front end of an upper bracket in a vehicle longitudinal direction is welded to a top surface of a rear cross member, and a weld zone between the rear cross member and the upper bracket includes, in a plan view of a vehicle, a central portion extending along a vehicle width direction and a curved end portion extending in a curved shape from each end of the central portion in the vehicle width direction toward a front side of the vehicle or a diagonally front side of the vehicle, to thereby reduce a stress on each vehicle-widthwise end of the weld zone between the rear cross member and the upper bracket configured to connect a towing tool attachment to the rear cross member.