An energy storage device includes: an electrode body including curved portions formed by winding an electrode; a container in which the electrode body is accommodated; and a cover plate structure including a cover plate closing the container. The electrode body is accommodated in the container while one end portion in a winding axis direction of the electrode body faces the cover plate structure. The energy storage device includes spacers (side spacers) that are attached to curved portions, and one end portion of the spacer abuts on a part of the cover plate structure.