A polymeric binder includes an ion-conducting polymer containing a polymer and a metal ion. The polymer is preferably selected from the group consisting of polyester, polyether, anionic polymer, polycarbonate, and silicone. An all-solid-state secondary battery includes an inorganic solid electrolyte, and the inorganic solid electrolyte in at least an electrode mixture layer or an inorganic solid electrolyte layer is bound together by the polymeric binder.