An energy storage device includes a positive electrode, a negative electrode, and an insulating layer arranged between these electrodes to electrically insulate these electrodes. 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 these particles. The composite layer of the negative electrode is made porous by a gap between the active material particles, and “−0.8≦Log B−Log A≦1.0” is satisfied in which in a pore distribution of the composite layer, a pore peak diameter is represented by A (μm), and in a pore distribution of the insulating layer, a peak diameter is represented by B (μm).