PURPOSE: To reduce a loss of material, and to improve a yield without necessity a lot of machines by forming a tooth form part and a chamfer part by means of cold forging.

CONSTITUTION: A tooth form billet M is inserted into a forming die 6, and a tooth form part 1 and a boss part 5 are extruded by means of cold forging. In that case, a chamfer part 2 is also formed simultaneously. Subsequently, a reverse tapered part 3 is cold-worked and formed on the tooth form part 1 by a coining press. The billet on which the reverse tapered part 3 is formed is grasped at least in three points by a chuck having a taper in the lead direction, on a pitch circle diameter, and the inside diameter is worked.