A power storage device having: a laminated body formed by providing a separator layer between a first electrode which is one of a cathode and an anode and a second electrode which is the other electrode; an electrolyte; and a package which houses the laminated body and the electrolyte. At least two first electrode composite sheets are included which are each obtained by integrating a first collector electrode, a first electrode active material layer provided on one principal surface of the first collector electrode, and a separator layer covering at least part of the one principal surface, and the other principal surface of the first collector electrode of one first electrode composite sheet out of the at least two first electrode composite sheets is opposed to, and bonded to, the other principal surface of the first collector electrode of the other first electrode composite sheet.