A wheel bearing apparatus for a driving wheel is formed as a unit of a wheel hub, a double row rolling bearing and a constant velocity universal joint. The double row rolling bearing has an outer member with a body mounting flange mounted on a knuckle and double row outer raceway surfaces. An inner member includes the wheel hub and an outer joint member of the constant velocity universal joint. The wheel hub has an inner raceway surface corresponding to one of the double row outer raceway surfaces. The outer joint member has another inner raceway surface corresponding to the other of the double row outer raceway surfaces. Double row rolling elements are rollably arranged between the outer and inner raceway surfaces. Seals are mounted in an annular space opening formed between the outer member and the inner member. A sensor is fit into a mounting aperture formed in the knuckle. A pulser ring is mounted on the outer circumferential surface of the outer joint member. It opposes the sensor via a predetermined radial gap. The outer diameter of the pulser ring is smaller than the inner diameter of the knuckle.