To provide a bearing device for wheel of which the reliability is increased by maintaining a strength of a wheel attaching flange while attaining the miniaturization/weight-reduction of the device, and at the same time, and by increasing and stabilizing the slip torque of a hub bolt.

A bolt insertion hole 6a is drilled in the wheel attaching flange 6, and the hub bolt 7 on which a serration 7a is formed is press-fitted in the bolt insertion hole 6a in this bearing device for wheel. A tempering process is applied after a hub ring 4 is forged, and at the same time, a specified hardened layer 7b is formed by a high-frequency induction hardening on the surface of the serration 7a of the hub bolt 7. Therefore, the strength of the wheel attaching flange 6 is increased, and at the same time, a sufficient difference in harness between the hub bolt 7 and the bolt insertion hole 6a can be ensured. The inner peripheral surface of the bolt insertion hole 6a is plastically deformed, and the serration 7a sufficiently bites into the bolt insertion hole 6a. Thus, the fixing force of the hub bolt 7 can be increased and stabilized without impeding the assembly workability.