A front cross member is installed between a pair of (right and left) front side members, and a plate-shaped sub-cross member, as a mounting member for a suspension or the like, is installed ahead of the front cross member. The front cross member and the sub-cross member are coupled by a backbone brace which is secured to the front cross member and the sub-cross member at positions in right and left portions of the front cross member and the sub-cross member by bolts or the like.