The present invention provides a highly reliable energy storage device capable of preventing a reaction current from flowing in a carbon nanotube electrode by ionizing a catalyst metal or a substrate metal to cause the metal to flow out to an electrolytic solution. An energy storage device of the present invention includes: at least a pair of electrode bodies that are a cathode and an anode; and an electrolytic solution. At least one of the electrode bodies is configured such that a layer of carbon nanotubes is formed on an electric conductor. A coupling region where one ends of the carbon nanotubes are coupled to and electrically connected to the electric conductor and a non-coupling region where ends of the carbon nanotubes are not coupled to the electric conductor are formed on a surface of the electric conductor. The carbon nanotubes having one ends connected to the coupling region are toppled to cover a surface of the non-coupling region.