WHEEL BEARING DEVICE

One object of the present invention is to provide a wheel bearing apparatus which does not cause any damage on the elastic member even if any linear scratch would be caused on the fitting surface of the outer member by the cap during fitting thereof and improve the sealability of the fitting portion and the reliability of the wheel bearing apparatus. For achieving the object mentioned above, there is provided a wheel bearing apparatus comprising an outer member; an inner member including a hub wheel and at least one inner ring, double row rolling elements contained between the outer raceway surfaces and inner raceway surfaces respectively of the outer member and the inner member; and a first cap press-fitted into an inboard-side opening of the outer member, the first cap comprising a cylindrical fitting portion press-fitted into an inside fitting surface of the outer member and a bottom portion extending radially inward from the fitting portion to cover the inboard-side end of the inner member, and the first cap being integrally adhered on its inboard-side outer circumference of the fitting portion with an elastic member of synthetic rubber via vulcanized adhesion and the elastic member projecting radially outward beyond the outer diameter of the fitting portion characterized in that the inner circumference of the inboard-side end of the outer member is formed by an inside fitting surface into which the first cap is press-fitted and a retracted surface formed inboard-side from the inside fitting surface via a step portion and having a larger diameter than that of the inside fitting surface, and that the elastic member is press-contacted against the retracted surface with being elastically deformed.