PROBLEM TO BE SOLVED: To provide a metal film such as gold having mesoporous structure which has not been realized before.SOLUTION: By applying a voltage to an electrode in a micelle solution of an amphiphilic block copolymer conjugated with metal compound such as gold to deposit the micelle on the electrode, a mesoporous film of the metal is formed on the electrode. Thus, a mesoporous metal film which has not been produced before is easily realized with stable quality. The pore diameter of the mesoporous metal film can be controlled in a wide range. Therefore, the mesoporous metal film has highly uniform pore diameters.SELECTED DRAWING: Figure 5