BEARING DEVICE ADAPTED FOR USE IN WHEEL AND PROVIDED WITH ROTATIONAL SPEED DETECTION DEVICE

One object of the present invention is to provide a wheel bearing apparatus provided with a rotational speed detecting apparatus which can solve problems of prior art and thus improve the reliability of the wheel bearing apparatus. According to the present invention, there is provided a wheel bearing apparatus provided with a rotational speed detecting apparatus characterized in that a cup-shaped cap is coated by preserving film and mounted on the outer member, the cap being press-formed of non-magnetic steel sheet and comprising a cylindrical fitting portion press-fitted into the inner circumference of the inner-side end of the outer member, a disc portion extending radially inward from the fitting portion and opposing to the pulser ring via a small axial gap, and a bottom portion extending from the disc portion via a bent portion to cover the inner-side end of the inner member; and that the rotational speed sensor is arranged oppositely to the pulser ring via the disc portion of the cap to which the rotational speed sensor is closely arranged.