To obtain a clean surface excellent in smoothness in a copper coating method or a copper lining method by a non-addition bath.

The copper coating method has a stage where the surface of a base material is subjected to copper plating of a thickness above the final finish thickness in a non-addition bath, a stage where the surface of the copper plating is subjected to mechanical grinding, and a stage where the mechanically ground copper plating surface is subjected to electrolytic grinding to the final finish thickness. The copper lining method has a stage where a copper electrocasting layer is formed on the surface of a base material in a non- addition bath, a stage where the surface of the copper electrocasting layer is machined and finished into a required copper electrocasting layer thickness, and a stage where the machined copper electrocasting layer surface is subjected to electrolytic grinding to be smoothened, and the deformed layer is removed and cleaned.