[Problem] To provide a technique for a battery-packaging material made of a film-form laminate in which at least a base material layer, an adhesive layer, a metal layer, and a sealant layer are laminated successively, wherein: electrolytic solution resistance is further improved by including a polyester film in the base material layer; cracks and pinholes are less likely to be created at the time of forming the polyester-film-including base material layer; and formability is improved. [Solution] This battery-packaging material is made of a laminate in which at least a base material layer, an adhesive layer, a metal layer, and a sealant layer are laminated successively, wherein: the base material layer includes a polyester film; and the metal layer is an aluminum foil in which the 0.2% proof stress at the time of performing a tensile test in a direction parallel to the rolling direction is from 55 to 140 N/mm2.