To prevent a wheel from falling off from a vehicle due to falling-off of a disc of the wheel of the vehicle during traveling from a hub.

In a fastening part of the wheel in the vehicle such as an automobile, an outer cylinder threaded in a fastening direction by rotation of an axle is screwed into a faucet of the hub, and the outer cylinder is made to abut on the disc by propulsion force of the outer cylinder when fastened by the rotation of the axle. Since the outer cylinder only abuts on the disc of the wheel by the rotation of the axle, the outer cylinder can be easily removed in short time during a puncture repair, etc.