A power storage device includes an electrode stack including a plurality of electrodes, a separator, and a resin sealing portion. The plurality of electrodes include a bipolar electrode. The bipolar electrode includes a current collector, a positive electrode active material layer, and a negative electrode active material layer. The sealing portion includes a first adhesive portion adhered to the current collector, a second adhesive portion adhered to the current collector, a first reinforcing portion bonded to the first adhesive portion, a second reinforcing portion bonded to the second adhesive portion, and an end surface welded portion. A water vapour transmission rate of the end surface welded portion is less than a water vapour transmission rate of the first adhesive portion and a water vapour transmission rate of the second adhesive portion.