PURPOSE: To prevent the thermal deformation of machine structure by detecting the temperature and mechanical displacement of the machine structures constituting a discharge machining device and driving a blowing fan cooling the machine structures and a cooler unit based on the detection results.

CONSTITUTION: A discharge machining device discharge-machines a work 6 submerged in a machining liquid in a machining tank 5 with the discharge energy applied through an electrode 8. At this time, the temperature of the machining liquid is increased, and the radiation heat is generated from heat generating sources, e.g., the upper face of the machining liquid, the machining tank 5, and a table 4, thus machine structures including a column 2 is heat-deformed. Then, a temperature sensor 9 and an inclination sensor 10 detecting the inclination displacement of the machine are installed inside the machine proper, and on the other hand, a cooler unit 11, such as a low temperature air generator, and a blowing fan 12 are arranged. When a temperature rise of the machine structures is detected by the temperature sensor 9, the blowing fan 12 is operated, and when the inclination of the columne 2 is detected by the inclination sensor 10, the cooler unit 11 is operated respectively.