Abstract: An energy storage device having sufficient energy density and sufficient power is provided. In this embodiment, an energy storage device that includes a negative electrode containing an active material layer including an active material is provided. The active material layer includes particulate graphite as the active material. A particle diameter frequency distribution of the graphite includes a first peak and a second peak which appears in a region where a particle diameter is larger than a particle diameter of the first peak, the particle diameter of the first peak is equal to or less than 10 ?m and the particle diameter of the second peak is more than 10 ?m. The active material layer further includes a particulate high hardness active material which has higher hardness than the graphite.