The electricity storage device includes an electrode assembly, a case, and a holding tape. The electrode assembly further includes a bottom surface, which is supported by an inner bottom surface of the case, two end faces in a lamination direction, which are joined to the bottom face, two side surfaces, which are joined to the bottom surface and intersect with the end surfaces, and two corner sections, which are formed from the bottom surface and the side surfaces. Each corner section includes a chamfered section, and a border section between the chamfered section and the bottom surface. The holding tape covers the border section from the bottom surface in a direction parallel to the bottom surface and orthogonal to the stacking direction, further inward of the electrode assembly than the side surface.