A wheel suspension system for suspending wheels rotatably supported by axle members for a vehicle is comprised of a pair of trailing arms which extends in a vehicle longitudinal direction and are connected to the axle members, respective; a pair of torsion bar cases which extend in a vehicle lateral direction and whose lateral outside portion is connected to the trailing arm; a pair of torsion bars which are connected to lateral inside portions of the torsion bar cases and whose lateral outside portions are connected to a vehicle body; and a connecting beam which extends in the vehicle lateral direction and connects the pair of torsion bar cases.