A power storage device packaging material has a structure in which at least a substrate layer, a first adhesive layer, a metal foil layer having an anticorrosion treatment layer on either side or both sides thereof, and a sealant layer are laminated in this order. In the packaging material, the sealant layer is formed of a resin composition containing polyolefin, and the sealant layer has at least one crystallization temperature peak in a temperature range of about 100° C. to about 120° C.