Front side frames 1 of a vehicle are each vertically connected through a corresponding one of joint members 7 to a cross member 2 configured to support a suspension arm below the front side frame 1. The joint members 7 are each coupled to a back end of a corresponding one of extension frames 4. This allows the front side frames 1 and the cross member 2 to share the load experienced by the extension frames 4 in a frontal collision of the vehicle.