EXTERIOR MATERIAL FOR ELECTRICITY STORAGE DEVICE

A packaging material for a power storage device, comprising at least: a substrate layer; a metallic foil layer with an anti-corrosion treatment layer being disposed on one face or both faces thereof; and a sealant layer in this order, wherein the sealant layer includes a polypropylene-based resin (A) and 1 to 40% by mass of incompatible component (B), and maximum seal strength Sin an adhered portion resulting from adhesion by heat-sealing the packaging material is 35 N/15 mm or more, and in addition, the packaging material for a power storage device satisfies the following requirements (1) or (2): (1) a ratio S/Sof seal strength Sto maximum seal strength Sin a stable range is 0.3 or more; (2) a ratio S/Sof average seal strength Sto maximum seal strength Sis 0.3 or more.