To provide a wheel nut which does not require the adjustment for the precision of the fitting (contact) between the outer peripheral surface of the cylindrical section of the nut body and the inner peripheral surface of the cylindrical section of a washer, and can reduce the cost for the manufacture/assembly, and also, to provide a wheel bolt which does not require the adjustment for the precision of the fitting (contact) between the outer peripheral surface of the spindle-like section of the bolt body and the inner peripheral surface of the cylindrical section of the washer, and can reduce costs for the manufacture/assembly.

The fitting (contact) position of the tapered form diameter expanded surface 2b of a bolt insertion hole 2a and the tapered outer peripheral surface 20b of the washer 20 is adjusted with the positioning between the seat surface 12a of a flange section 12 and the end surface 20a of the washer 20 when the wheel nut 100 is assembled as a reference. Thus, the fastening between a hub 1 and a disk wheel 2 is precisely performed, and slacking of the wheel nut 100 and a breakage of the wheel bolt 3 become hard to occur.