A capacitor includes a film previously provided on both sides or one side of a collector by anodizing or the like, further a conductive layer provided on the film, and a polarizable electrode layer as an electrode portion on the conductive layer. Thus, the capacitor suppresses the reaction between a driving electrolyte and the collector after a long time of use because the reactivity between the film previously provided on both sides or one side of the collector and the driving electrolyte is low. Furthermore, since the conductive layer is provided, it is possible to reduce an initial contact resistance on the surface of the collector, and to enhance an effect of suppressing performance deterioration by the film.