PURPOSE: To substantially eliminate the possibility that an operator should touch an electrolyte solution, by setting a wafer not in contact with the electrolyte solution, then immersing the wafer in a solution to electrolyze the wafer, and taking out the wafer, again not in contact with the electrolyte solution.

CONSTITUTION: A frame of an electrolytic cell 5 is attached to a shaft so as to freely rise and fall by means of the shaft. The electrolytic cell 5 has an electrode 3 therein and a cover 4. An aperture 6 of the electrolytic cell 5 has, on the upper part thereof, a setting portion 7 for a wafer 25. In a press unit 9 for pressing the wafer 25 in contact with the setting portion 7, a press member 18 presses the back side of the wafer 25 via a spring 17 provided on the cover 4. Thus, when the cover 4 is closed, the press unit 9 can automatically press the wafer 25 in contact with the setting portion 7.