A probe device for testing a wafer divided into IC chips has a vessel that accommodates a wafer mounting stand and a flexible probe card having contactor bumps. The vessel is configured in a separatable manner of a grounded aluminum cover portion to which the probe card is integrally fixed and a base portion fixed to the wafer mounting stand. The interior of the vessel is sealed with the wafer and the probe card facing each other therein. A space above the probe card forms a damper chamber into which a fluid is introduced in such a manner that the pressure thereof presses the bumps on the probe card against the wafer. Bumps in a peripheral edge portion of the probe card are placed into contact with electrodes in a peripheral edge portion of the vessel, and thence to a test head. The above configuration can prevent the effects of external electrical noise and thus enable stable electrical measurements unaffected by changes in ambient temperature. In order to remove the effects of thermal expansion of the probe card and the wafer, graticules are formed in each of X and Y directions around an array of bumps. The coordinate positions of the bumps on the probe card under normal temperature conditions are previously stored in a storage unit, the graticules are read by an imaging unit when the probe card has thermally expanded, the current coordinate positional data for the bumps is obtained from the results of this read and the stored bump coordinate positional data, and this is used to control the position of the mounting stand.