While rotating a spindle 34, the circular hole 15 is worked using a cutting tool 39. Before or after the working operation of the circular hole 15, a chuck 36 is translated in a direction perpendicular to the rotation center axis of the spindle 34 by a slider 35. And, the flat surface 29 as well as the stepped surfaces 31, 31 and inner surfaces 38, 38, which are respectively composed of partially tubular surfaces, are cut or worked.