A thin energy storage device having high capacity is obtained. An energy storage device having high output is obtained. A current collector and an active material layer are formed in the same manufacturing step. The number of manufacturing steps of an energy storage device is reduced. The manufacturing cost of an energy storage device is suppressed. One embodiment of the present invention relates to a method for manufacturing of an electric double layer capacitor, or a lithium ion capacitor, which includes porous metal electrodes formed by removing a metal from an alloy foil, and an electrolyte provided therebetween. A surface area per volume of the porous structure is greater than or equal to 100 m2/cm3.