PURPOSE: To provide a smooth polished surface freed from sagging by a method wherein during polishing of a metal, physical polishing is used in combination with electrolytic polishing.

CONSTITUTION: By applying an electric field on a material made of a metal to be polished maintained in a wet state, the material to be polished is brought into anode polarization or cathode polarization on the polishing surface of a polishing material, and with this state, physical polishing is applied on the material to be polished by means of the polishing material to perform polishing of the material to be polished. The polishing disc of a device is formed by a conductive material, formed by aluminum and titanium or an alloy of them, being stable against negative and positive polarization, and a barrier to prevent the occurrence of short-circuit therebetween is formed between the polishing disc and the material to be polished. The polishing disc and the material to be polished form two poles, and a power source to apply a proper voltage thereon is situated. In order that a metal being the material to be polished is polarized by applying an electric field, liquid, e.g. water, acetate, for always maintaining a wet state is fed to the material to be polished. By simultaneously effecting physical polishing and electrolytic polishing, the material to be polished having approximately complete smooth polishing surface can be provided by means of a synergetic effect produced by the two polishing.