Energy storage device and energy storage unit

An energy storage device (10) including a positive electrode (410), a negative electrode (420), a separator (431 or 432) disposed between the positive electrode (410) and the negative electrode (420), and a non-aqueous electrolyte, wherein the negative electrode (420) includes a negative electrode active material layer (422) containing a non-graphitizable carbon as a negative electrode active material, and the negative electrode active material has a negative electrode active material weight per unit volume of the negative electrode active material layer (422) of 0.92 g/cc or more and 1.13 g/cc or less and a particle size D90 of 4.3 µm or more and 11.5 µm or less, the particle size D90 being a particle size in particle size distribution in which a cumulative volume is 90%.