To slash an excess time for carrying a work to or from a machine tool, and also shorten a span of turnover time by turning over the work, whose one side and the other side are required to be machined, in the machine.

A work gripping means, which has delivered a work W to a work holding means 10 is moved up to a retreat position along with the travel of a tool post in the Z-axial direction. If this tool post is moved up to the retreat position, a control unit drives a turnover rotary table 15 and a work mounting part 16a is turned over as far as 180 degrees together with the work W. After completion of the turnover of the work W, the work gripping means is made to travel up to a work receiving position along with the travel of the tool post in the Z-axial direction, and the work W mounted on the work mounting part 16a is gripped by a gripping pawl. Then, the work gripping means is moved up to the retreat position on the Z-axis intact, separating the work W from the work holding means 10.