PACKAGING MATERIAL FOR BATTERIES, METHOD FOR PRODUCING SAME, POLYBUTYLENE TEREPHTHALATE FILM FOR PACKAGING MATERIAL FOR BATTERIES, AND BATTERY

A packaging material for batteries, which is not susceptible to warping, while having excellent formability. A packaging material for batteries is configured from a laminate that is sequentially provided at least with one or more substrate layers, a barrier layer, a cured resin layer and a thermally fusible resin layer in this order. At least one of the substrate layers is formed of a polybutylene terephthalate film; and the value (X/Y) which is obtained by dividing the puncture strength X (N) of the laminate by the thickness Y (μm) of the polybutylene terephthalate film, the puncture strength X (N) being determined by piercing the laminate from the substrate layer side by a method that complies with the prescription of JIS Z1707 (1997), is 1.02 N/μm or more.