Disclosed is a secondary battery comprising a reaction vessel and a collector built-in at least one of the positive electrode side and the negative electrode side of the reaction vessel. The positiveelectrode side and the negative electrode side are separated from each other by an ion conductive separation unit. In the reaction vessel, an organic matter other than metal complexes and radicals which is reversibly oxidized/reduced is used as an active material together with a supporting salt in a liquid state. The active material contained in the liquid is charged/discharged on the surface of the collector.