Abstract: A rear wheel suspension device comprises a radius rod extending substantially in the longitudinal direction of a vehicle body, pivotally supported at one end and supporting the rear wheel axis at the other end, and a lower arm supporting at one end the rear wheel axle in cooperation with the radius rod and pivotally supported at the other end on the vehicle body, the radius rod extending substantially at 90 degrees to the lower arm. A resilient bush supporting the radius rod is formed to be relatively more resilient in the back-and-forth direction of the wheel, and a resilient bush supporting the lower arm in the transverse direction of the wheel is substantially rigid. With this arrangement, the movements of the rear wheel due to side forces in the toe-in and toe-out directions are suppressed for maintaining roadability, and at the same time the compliance in the back-and-forth directions of the rear wheel is enhanced for improved riding comfort.