To enable plural screw holes and supporting surfaces to be machined easily on the outer circumferential surface of a spherical jointing body by positioning and controlling the spherical jointing body by means of plane moving position control, normal/reverse turning motion control around a holding shaft line and pitching movement control of a holding shaft line.

A spherical jointing body is subjected to plane moving position control in X shaft and Y shaft directions as lateral and longitudinal directions by means of a plane moving position control part 5 and subjected to normal/ reverse turning motion position control around the holding shaft line of the spherical jointing body by means of normal/reverse turning motion position control part 15. Furthermore, by making pitching movement control on the holding shaft line by means of the pitching movement control part 11, mutual positioning control between the spherical jointing body and a cutting tool 22 is carried out. After positioning, the cutting tool 22 descends in Z shaft direction by means of a tool position control part 24 and screw hole and supporting surfaces are machined by means of the cutting tool 22.