PURPOSE: To shorten the time for tool replacement by allowing a single spindle motor to work both for rotation of the spindle and rotation of the tool magazine and by providing possibility to index for a next tool continuously.

CONSTITUTION: According to a command for tool replacement, an NC device 2 rotates the Z-axis motor 19a to draw up the spindle mechansim 11 and tool magazine 20, which will then turn the spindle motor 12 and stop the spindle 11a at its decided position. If further the motor 19a is put in operation to raise the spindle mechanism 11 within the ATC zone, a cam allows the spindle's grip part to release the grasp of arbor 21b. When the spindle mechanism 11 rises further, the slider member 20e of the tool magazine 20 runs against a stopper 23 to stop the rise of the tool magazine 20, allowing only the spindle mechanism 11 to rise, and the arbor comes loose from the spindle and a bevel gear 11b of spindle mechanism is put in meshing with the bevel gear 20c of the tool magazine. Then the tool magazine 20 is rotated by operating the spindle motor 12 to locate a next tool right under the spindle 11.