To provide a bearing apparatus for wheels having a rotation speed detection device in which the fixation of a sensor holder is maintained over a long period for improving reliability, in detecting the rotational speed of wheels.

The sensor holder 16 is provided with both a cover 17, made of sheet steel and having a cylindrical fitting part 17a to be pressed in the outer circumference 5c of an end part of an outward member 5; a flange part 17b, extended from the fitting part 17a in an inward radial direction; and a bottom part 17c extended in axial directions from the flange part 17b and a holding part 18, made of synthetic resin and connected to the bottom part 17c, in which a rotation speed sensor 19 is embedded. A paste-like, non-drying, liquid-sealing agent 26 is interposed between the outer circumference 5c of the end part of the outward member and the fitting part 17a of the cover 17. Thus, it is possible to maintain fixation of the sensor holder 16 over a long period, prevent infiltration of rainwater, dust, etc. in the detection part from the outside, and improve the reliability in detecting the rotational speed of wheels.