PURPOSE: To compensate the backlash of a feed controlling device and improve machining accuracy, by shifting a cutting tool in the direction of being subject to work reaction force in time of cutting and, after once keeping apart from the workpiece, shifting the cutting tool in a direction against said work reaction force.

CONSTITUTION: In case of machining the outer diameter of a bar cycle, the cutting tool 5 is traveled in rapid traverse up to a tool removal position 5b at the calculated X-axis' plus position. When the Z-axis feed of a work 1 gets through, as a cutting tool 5 shows in a position 5a. Next, the tool 5 is as well traveled in rapid traverse up to a scheduled cutting position 5c from the tool removal position 5b. In this state, the backlash of the feed controlling device is moved to the X-axis' plus side whereby the backlash of the feed controlling device in the X-axis can be compensated.