The wheel hub (30) includes a radial swaged portion (37) formed by a radially outward plastic deformation of one end thereof, whereby an inner ring (40) fitted onto the wheel hub (30) is united therewith. An outer joint member (72) of a constant velocity joint (70) is press-fitted into the wheel hub (30), causing serrations (81) on the inner periphery of the wheel hub (30) and a serrated shaft (82) of the outer joint member (72) to engage with each other. The mating parts (81,82) of the inner member (30) and the outer joint member (72) have undergone rust proof treatment.