An energy storage device comprising a negative electrode plate having a negative electrode active material layer of a carbonaceous composite material formed on a negative electrode collector, a positive electrode plate having a positive electrode active material layer capable of inserting and releasing lithium ions and a non-faradic reaction layer capable of accumulating and releasing electric charges upon physical adsorption-desorption of ions on the surface layer of the positive electrode active material layer and an insulator layer for electrically insulating the positive electrode plate from the negative electrode plate, the insulator layer being capable of permeating only mobile ions. The carbonaceous composite material comprises particles of graphite and/or amorphous carbon and activated charcoal, and the particles of the graphite and/or amorphous carbon and particles of the activated charcoal are united.