Drilling work is performed to a workpiece 5 on a table 2a of an M/C by a drill 2h mounted to an adapter part 2d. When drilling work is completed, the drill 2h is removed from the adapter part 2d, andaworkpiece gripper 2i is mounted to the adapter part 2d. The adapter part 2d descends, and the workpiece gripper 2i grips the drilled workpiece 5. The adapter part 2d then ascends to temporarily holdt he workpiece 5 in the M/C. In this state, the following workpiece 5' is placed on the table 2a of the M/C. Placement of the following work 5' onto the M/C is simplified by temporarily holding the drilled workpiece 5 in the M/C. To simplify workpiece placing and taking-out work, to dispense with a temporary placing space and to efficiently perform machining work.