An electric probing-test machine comprises a probe card having a plurality of probes contacted with chips of a semiconductor wafer and serving to apply test signal to a tester which judges whether circuits on the chips of the wafer are correct or deficient, a main chuck for holding the wafer at a test temperature, a system for cooling the main chuck, and a controller for controlling the cooling system. The main chuck includes a chuck top contacted directly with the wafer, a jacket arranged to conduct heat exchange relative to the chuck top, and a temperature sensor for detecting the temperature of the chuck top. The cooling system has a pump for supplying a coolant from a reservoir to the jacket. Responsive to temperature information detected by the temperature sensor, the amount of the coolant supplied from the reservoir to the jacket is controlled by the controller to thereby control the temperature of the chuck top.