To provide a bearing system for a wheel that allows good calking, secures strength by sufficiently forming a curing layer, and secures creep resistance.

The corner of an end surface of a single-row inner ring 5 facing in the outward direction of the bearing and the inner peripheral surface has a chamfering section 5a having a circular arc cross section. The single-row inner ring 5 is fixed to a hub ring 4 in a calking section 4c by calking a cylindrical section further projected to the end side of an inner ring engaging surface 4a of the hub ring 4 to the outer diameter side like a collar. The hub ring 4 is made of carbon steel, and the curing layer 20 is disposed in a surface section covering the range of the inner ring engaging surface 4a to a root section 22a of a hub flange 22. The position of the inner side end of the curing layer 20 lies on the end side of a rolling surface 3a of the single row inner ring 5, and on the central side of the chamfering section 5a of the single row inner ring 5.