PURPOSE: To perform stable high-precise machining, by a method wherein the weight of a workpiece is detected, a correction amount responding to a detecting value is read from a correction amount memory means, and an NC program is corrected by a deformation amount of a cross table.

CONSTITUTION: When a cross table 2, on which to place a workpiece 1, is driven with the aid of X-and Y-axis motors 32 and 33, a starting current proportioning the weight of the placed workpiece 1 flows through the motors 32 and 33, and it is found that the starting current also proportions a deformation amount of the cross table 2 produced by dint of the weight of the workpiece 1. Thus, the current value is compared with a current value stored in a correction data memory 55, a correction value of the cross table 2, responding to the current value, is decided, and after correction of an NC program is effected according to the correction value, shifting to machining is effected. As a result, stable high-precise machining can be performed irrespective of a deformation amount of the cross table 2.