To improve volumetric efficiency, enhance barrier property of gas and water and attain improvement of vibration resistance and shock resistance, by providing a metal thin film layer in at least an internal/external peripheral surface of a resin frame of a secondary battery.

A secondary battery 10 is constituted of a battery case 11, electrode unit 20 and an electrolyte with which the electrode unit is impregnated. The battery case 11 includes a frame-shaped resin frame 12 by integrally molding and two sheets of sheet-shaped covers 13 for closing an opening part of the resin frame 12. The resin frame 12 is integrally formed by injection molding. The resin frame 12, after molding at least in an internal peripheral surface and/or external peripheral surface, is formed with a metal thin film layer by a plastic plating process or the like. For instance, the resin film 12 is mounted in a plating jig, chemical etching, activation, electroless copper plating, nickel plating and chromium plating are successively performed, as a whole, a metal plating film of about 40μm thickness is formed.