To make a polymer solution penetrate every corners of an active material layer by forming the active material layer comprising an active material in which a porous polymer electrolyte is formed on the surface of the layer on a metal collector mainly comprising a porous metal body.

An active material mix paste comprising an active material particle, a binder, a solvent and a conductive auxiliary is applied on a substrate such as a porous metal foil and dried to form an active material layer. The active material layer comprising the active material particle thus obtained has a structure that the active material layer is mainly formed on a metal collector different from an electrode prepared by retaining it in a foamed metal and the active material layer becomes porous caused by evaporation of the solvent. Next, a polymer solution being a polymer electrolyte is retained in a hole portion formed between the active material particles in the active material layer and on a surface portion of the active material layer. Since the substrate has the holes, the air in the active material layer can be discharged through holes of the substrate and the polymer solution is uniformly penetrated in the active material layer.