An energy storage device, comprising: a positive electrode; a negative electrode; and an insulating layer arranged between the positive and negative electrodes to electrically insulate the positive and negative electrodes, wherein the negative electrode includes a composite layer containing active material particles, the composite layer of the negative electrode, and the positive electrode are arranged to face each other across the insulating layer, the insulating layer contains electrically insulating particles, and is made porous by a gap between the electrically insulating particles, the composite layer of the negative electrode is made porous by a gap between the active material particles, and the following relational expression is satisfied: − 0.8 ≤ LogB − LogA ≤ 1.0 in which in a distribution of pores in the composite layer, a pore peak diameter determined by a mercury intrusion method according to JIS R1655 at room temperature is represented by A (μm), and in a distribution of pores in the insulating layer, a pore peak diameter is represented by B (μm); wherein the active material particles in the negative electrode comprise non-graphitizable carbon, wherein an average primary particle diameter D90 of the active material particles in the composite layer is 3 μm or more and 18 μm or less, and wherein a particle diameter D90 corresponds to the cumulative quantity of smaller 90%-particles out of the measured particles when the particle diameter of each of at least 500 primary particles is measured, wherein the pore peak diameter of the composite layer is 0.5 μm or more and 1.5 μm or less, wherein the pore peak diameter of the insulating layer is 0.2 μm or more and 12 μm or less. a positive electrode; a negative electrode; and an insulating layer arranged between the positive and negative electrodes to electrically insulate the positive and negative electrodes, wherein the negative electrode includes a composite layer containing active material particles, the composite layer of the negative electrode, and the positive electrode are arranged to face each other across the insulating layer, the insulating layer contains electrically insulating particles, and is made porous by a gap between the electrically insulating particles, the composite layer of the negative electrode is made porous by a gap between the active material particles, and the following relational expression is satisfied: − 0.8 ≤ LogB − LogA ≤ 1.0 in which in a distribution of pores in the composite layer, a pore peak diameter determined by a mercury intrusion method according to JIS R1655 at room temperature is represented by A (μm), and in a distribution of pores in the insulating layer, a pore peak diameter is represented by B (μm); wherein the active material particles in the negative electrode comprise non-graphitizable carbon, wherein an average primary particle diameter D90 of the active material particles in the composite layer is 3 μm or more and 18 μm or less, and wherein a particle diameter D90 corresponds to the cumulative quantity of smaller 90%-particles out of the measured particles when the particle diameter of each of at least 500 primary particles is measured, wherein the pore peak diameter of the composite layer is 0.5 μm or more and 1.5 μm or less, wherein the pore peak diameter of the insulating layer is 0.2 μm or more and 12 μm or less.