PURPOSE: To reduce the cost of production of a stainless steel base plate, by performing combined electrolytic polishing on the plate at polishing pressure and electrolyzing electrical current density below prescribed values while impregnating a polishing soft porous synthetic resin with a polishing electrolyte made of a solution of a neutral salt and mixed with polishing abrasive grains.

CONSTITUTION: An electrolyte is impregnated into a polishing material 3 such as foamed polyurethane and foamed polyester as the material is pushed on a stainless steel plate 4 and electricity is applied between the plate and an electrode 5 to electrolytically polish the plate. At the same time, the polishing material 3 is slid relative to the plate 4 to polish it by abrasive grains. The density of electrical current for the electrolytic polishing and the pressure for the polishing by the material 3 are set at 0.5A/cm2 or less and 0.02kg/cm2 or less, respectively, to prevent the great consumption of the polishing material 3 and the abrasive grains to reduce the cost of the polishing. Since the electrolyte is impregnated into the polishing material 3 to bring the electrolyte into good contact with the base plate 4, the performance of the polishing is high enough to enable desired polishing even if the polishing pressure and the electrolyzing current density are made low.