PURPOSE: To reduce the number of stocks, simplify the confirm operation with respect to thread pitch and prevent the waste of parts by threading two kinds of threads on one nut or bolt.

CONSTITUTION: A wheel nut body 1 has the shape of a cap nut with an uneven or hexagonal upper portion. A hole 2 has an opening in the center of the lower portion. A thread forming surface 8 which is the internal peripheral surface of the hole 2 is threaded when the wheel nut body 1 is fixed by a suitable fixture. The threading operation is conducted by a tap 5 of the M12 Standard of a 1.5 mm thread pitch in the hole 2. Then the tap mounted on a threading device is substituted by a tap 5a of the M12 Standard of a 1.25 mm thread pitch for threading in the same manner. The threading start by the tap 5a is set to be just identical to the threading start position of the above-mentioned thread groove 3 of 1.5 mm.