A solid electrolyte membrane (13) is arranged on a surface of an anode (11) between the anode (11) and a substrate (B) that serves as a cathode. The solid electrolyte membrane (13) is brought into contact with the substrate (B). At the same time, a metal film (F) is formed on the surface of the substrate (B) by causing metal to precipitate onto the surface of the substrate (B) from metal ions through application of voltage between the anode (11) and the substrate (B) in a first contact state where the solid electrolyte membrane (13) contacts the substrate (B). The metal ions are contained inside the solid electrolyte membrane (13).