To provide a bearing device for a driving wheel which can achieve reduction of the weight and the size, in which a plastic joining part has sufficient strength even if a large moment load acts on a device, and which can increase strength at a stem and has durability.

The bearing device for the driving wheel is so constituted that one inner rolling face 1a of plural rows of rolling bearings 2 is formed on the outer periphery of a hub ring 1, and the other inner rolling face 14a is formed on the outer periphery of an outer joint member. The stem 17 formed to the outer joint member 14 of a constant velocity universal joint 3 is internally fitted to the hub ring 1, and a hardened irregularity part 5 is formed to the inner diameter of the hub ring 1. The hub ring 1 and the outer joint member 14 are integrally plastically joined by enlarging in diameter of a fitting part 17b formed to the stem 17 to bite into the irregularity part 5. The irregularity part 5 is constituted of crossing grooves formed by making a plurality of independent annular grooves perpendicular to grooves in the axial direction. A projection part of the annular groove is formed into an asymmetrical shape so that a tip angle becomes approximately 90° and an inclination angle on the outboard side becomes an acute angle.

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