According to the present invention, there is provided a seal step (ST105) storing an electrode laminate in which a separator is disposed between a positive electrode and a negative electrode and an electrolyte within an exterior body constituted by a laminate film and sealing the exterior body; a pressure application step (ST106) of applying a pressure to the exterior body in which the electrode laminate is stored by means of a flat plate press working or so forth; charge step (ST102) of charging up to a full charge; a gas removal step (ST107) of unsealing the exterior body and removing gas generated within the exterior body at the charge step; and a re-seal step (ST108) of sealing the exterior body after the gas removal step.The number of times of the gas removal steps is small and an influence of gas on battery characteristics is suppressed.