A method of correcting a change of position of a machine tool having at least two control axes. A position change check simulator (14) obtains a ratio (R2) of amounts of movement of respective axes (Xe1, Ye1) obtained from output values of position detectors (8X, 8Y) for detecting a position of the machine tool, and further, obtains a ratio (R1) of predicted amounts of movement of the respective axes obtained from a machine position predicted on the basis of distribution pulses (Xp5, Yp5) of the respective axes, assuming that a servo system has a first order lag. A position correcting means (12) outputs a correction pulse (Xc1, Yc1) so that the ratio (R2) of actual amounts of movement becomes equal to the ratio (R1) of the predicted amounts of movement. This correction pulse (Xc1, Yc1) is added to command pulses (Xp1, Yp1), and accordingly, an abrupt machining error occurring at the beginning and just before the end of machining, and during the machining at corners of a machined article, can be eliminated.