PURPOSE: To contrive the correction of dimensional error due to thermal displacement and the like without temporarily stopping the working program during the carrying out thereof by correcting the off-set value, with which the real position of a tool or a workpiece is corrected so as to compute the real position, during the carrying-out of the working program so as to correct the coordinates.

CONSTITUTION: In the case that the value of the dimensional error due to thermal displacement and change of sharpness of a tool G is known, the dimensional error as an off-set correction value is input by an off-set correction value inputting means 24 during the operation by the working program, and the off-set value is corrected to this off-set correction value by an off-set value correcting means. With this operation, at the time of moving a tool G or a workpiece W, the real position is obtained by a real position computing means by off-setting the detected real position, which is obtained by a detected real position output means, with the off-set value, and on the basis of this real position, a movement control means 20 moves the tool G or the workpiece W to a target movement position.