PURPOSE: To shorten machining time by employing a pipe having fixed inner diameter and bending the pipe inwardly, at the end thereof, by means of a forming jig having a freely rotatable free ball.

CONSTITUTION: A V-groove 16 for forming the protrusion 14 of a yoke 10 is cut by means of a byte and a groove 18 for cutting the yoke 10 from a pipe P is formed at a predetermined position in the inner face of the pipe P. The pipe P is then bent, at the end thereof, by means of a forming jig 22 fixed to a tool post 20 of an NC automatic machine tool, for example, and engaged rotatable with a large diameter free ball 28 thus forming the protrusion 14 of the yoke 10. Finally, the pipe P is cut off at the position of the groove 18 through a cutting means thus manufacturing the yoke 10. According to the invention, machining time can be shortened.