PURPOSE: To improve the productivity by executing the multi-spindle machining of works, efficiently remove chips, and provide accurate coincidence of the phase in thread cutting.

CONSTITUTION: A main spindle supporting body 4 is divided into a plurality of positions of the angle of rotation, and fixed at the position. A plurality of main spindles 7a, 7b, 7c mounted on the main spindle supporting body 4 on the stopped position are located in the supply/discharge position, and the machinging position of the work. Chucking jaws mounted on the main spindles 7a, 7b, 7c hold the works within the main spindles. The main spindles 7a, 7b, 7c are driven by a driving means connected at the stopped position of the main spindle supporting body 4. While the work is supplied/discharged to/from the main spindle 7a at the supply/discharge position, the works to be held by the main spindles 7a, 7b, 7c at the machining position are simultaneously machined.