Abstract: A temperature change of a machine tool which is influenced by a heat generating source is detected by a temperature sensor. A temperature change having substantially the same time constant as a time constant of a thermal distortion of the machine tool is calculated by using the detected temperature change. A machining error is corrected on the basis of the thermal distortion corresponding to the calculated temperature change. According to a method and an apparatus for compensating for the thermal distortion in the machine tool, it is possible to perform the compensation relative to the thermal distortion with high precision. The invention is applied to a machine tool such as a machining center and an NC lathe.