A suspension system comprises front and rear cantilever spring arms. First end portions of the arms are fixed to a vehicle body. Second end portions of the arms extend toward a member for supporting a wheel. The second end portions are connected to each other by means of a curved section. The spring arms are formed integrally with the curved section through the medium of the matrix resin and the fibers so as to be V-shaped as viewed from above. A joint assembly is fixed to the curved section, and a hub carrier is mounted on the assembly.