parts and to simplify parts control thereby reducing the cost of the seal rings moreover the design is such that a contact point p of an extension line u03b1 of the contact angle of the inside rolling members 9 and the outer peripheral surface of the cylindrical portion 32 provided on the hub 2 is placed at the base end portion or the portion of male spline 29 of the cylindrical portion 32 which is not crimped outward in the radial direction hence a large load is not applied from the rolling members 9 on the inside to the crimped portion 33 which from a processing point of view is difficult to make thick fig8 shows a fourth embodiment of the present invention this embodiment is opposite to the abovementioned third embodiment in that a female spline 30 is formed on the side of a hub 2 corresponding to the first inner ring provided with a flange 11 for securing a road wheel and a male spline 29 is formed on the side of an inner ring 3 corresponding to the second inner ring and serving also as the outer ring of a constant velocity joint accordingly a cylindrical portion 32 forming a crimped portion 33 on a tip portion thereof is provided on the side of the inner ring 3 while a small diameter portion 31 which is closely fitted to the outer peripheral surface of the base end portion right end portion in fig8 of the cylindrical portion 32 is provided on the inner peripheral surface side of the hub 2 in.