A lithium ion secondary battery having an electrode body including a positive electrode made of a positive electrode active material layer joined to a current collector, a negative electrode made of a negative electrode active material layer joined to a current collector, a separator which is disposed between the positive electrode and the negative electrode and retains an electrolytic solution containing lithium ions, and a porous adhesive resin layer which retains the electrolytic solution and joins the separator to at least one of the positive electrode active material layer and to the negative electrode active material layer, the electrode body being sealed into a packaging bag, wherein an adhesive resin film capable of absorbing the electrolytic solution and gelling adheres the electrode body to the packaging bag.