To provide a wheel bearing device with a rotational speed detector, preventing separation of a sensor holder from a core and also achieving improved detection accuracy and reliability.

The core 24 has an outside diameter cylindrical part 24a press-fitted into the end of an outward member 3 and formed with a circular hole 26, a rising plate part 24b extending radially inward from the side outward of the bearing of the outside diameter cylindrical part 24a, an inside diameter cylindrical part 24c extending from the rising plate part 24b to the side inward of the bearing, and an inside diameter part 24d extending radially inward from the inside diameter cylindrical part 24c. The sensor holder 20 is insert-molded in and integrally coupled to a portion extending over the rising plate part 24b and inside diameter cylindrical part 24c from the outside diameter cylindrical part 24a, a seal member 25 is joined to the inside diameter part 24d, and the inside diameter part 24d is arranged to be evacuated from the detection part of a rotational speed sensor 29 to the side outward of the bearing. Therefore, an air gap between the detection part and a magnetic encoder 28 can be reduced, and high magnetic flux density can be provided.