To provide a storage battery electrode including an active material layer with high density that contains a smaller percentage of conductive additive. To provide a storage battery having a higher capacity per unit volume of an electrode with the use of the electrode for a storage battery. A slurry that contains an active material and graphene oxide is applied to a current collector and dried to form an active material layer over the current collector, the active material layer over the current collector is rolled up together with a spacer, and a rolled electrode which includes the spacer are immersed in a reducing solution so that graphene oxide is reduced.