PURPOSE: To reduce leakage currents and self-discharge without increasing internal resistance by forming a separator consisting of an insulating layer and a metallic layer laminated onto the insulating layer.

CONSTITUTION: Polarizable electrodes 1, 2 are manufactured by press molding activated carbon fibers or a substance in which a binder is mixed with activated carbon. The separators 3, 9 separate the polarizable electrodes 1, 2, and are shaped from insulating layers 4, 5 composed of the nonwoven fabric of polypropylene, polyethylene, etc., or a porous plastic film and metallic layers 6, 10 held by the insulating layers 4, 5. The metallic layer 6 is shaped from a valve action metal such as Al, Ti, Ta, etc., in thickness of 10W200μm, a noble metal such as Au, Pt, etc., or a wire gauze having a high mesh and consisting of stainless. A member in which the valve action metal such as Al, Ti, Ta, etc. or the noble metal such as Au, Pt, etc., is evaporated onto one surface of an insulating layer 11 can also be used in place of the wire gauze as the metallic layer 10 for the separator 9. Accordingly, the member in which the metallic layer is laminated onto the insulating layer is employed as the separator, thus reducing leakage currents without increasing internal resistance.