PURPOSE: To correct all thermal deformations including those of a motive power transmitting mechanism, a work and a frame by detecting the condition of a moving body in a fixed position in such a manner that the condition can be converted into a fixed temperature, and controlling a servo system so that the position at which the work is actually machined agrees with a set value at a fixed temperature.

CONSTITUTION: In order to correct errors in machining of the driving line of a moving body and a work W or a frame portion due to thermal influences, the condition in which the moving body moves is detected in a fixed position in such a manner that the condition can be converted into a fixed temperature by a master scale 12. The detected value is compared with that of a closed loop control system, and thereby the closed loop control system is corrected by a correcting means 17 so that the position at which the work is actually machined agrees with a set value at a fixed temperature.