A power storage device includes a plurality of power storage modules, a first connecting plate, and a second connecting plate. Each of the plurality of power storage modules includes a plurality of power storage cells, a first end plate, and a second end plate. The first end plate includes a first main plate and a first sub-plate. The first sub-plate includes a first securing hole. The first main plate and the first sub-plate are provided to be connected to each other in at least two positional relationships with different positions of the first securing hole. The first connecting plate includes a first reference securing hole aligned with the first securing hole. The first securing hole is secured to the first reference securing hole by a first securing member.