A power storage device packaging material comprising a structure including at least a substrate layer, an adhesive layer, a metal foil layer, a sealant adhesive layer, and a sealant layer, which are laminated in this order, wherein the adhesive layer is a two-part curing type polyurethane adhesive including a base resin made of a polyol, and a hardener, wherein the hardener is an aromatic or aliphatic isocyanate and the molar ratio of the isocyanate group of the hardener to the hydroxyl group of the base resin is in the range of 1 to 10; and the adhesive layer has a yield stress in the range of 3500 to 6500 N/cm 2 and breaking elongation of 45 to 200% in a stress-strain curve determined by a tensile test at a tension rate of 6 mm/min, wherein the yield stress and breaking elongation are measured by: applying the polyurethane-based adhesive on an AL plate so that the thickness of the sample becomes 4.0 μm; applying an aging treatment, which is leaving the same standing at 60 °C for 6 days; peeling the adhesive layer from the AL plate after aging; preparing a measurement sample by cutting the adhesive layer into a width of 5 mm and a length of 20 mm; applying a tensile load to the measurement sample at a tension rate of 6 mm/min by using a tensile tester while holding both ends in the longitudinal direction of the measurement sample with a jig; and charting the relationship between the load and the deformation in a stress-strain curve. the adhesive layer is a two-part curing type polyurethane adhesive including a base resin made of a polyol, and a hardener, wherein the hardener is an aromatic or aliphatic isocyanate and the molar ratio of the isocyanate group of the hardener to the hydroxyl group of the base resin is in the range of 1 to 10; and the adhesive layer has a yield stress in the range of 3500 to 6500 N/cm 2 and breaking elongation of 45 to 200% in a stress-strain curve determined by a tensile test at a tension rate of 6 mm/min, wherein the yield stress and breaking elongation are measured by: applying the polyurethane-based adhesive on an AL plate so that the thickness of the sample becomes 4.0 μm; applying an aging treatment, which is leaving the same standing at 60 °C for 6 days; peeling the adhesive layer from the AL plate after aging; preparing a measurement sample by cutting the adhesive layer into a width of 5 mm and a length of 20 mm; applying a tensile load to the measurement sample at a tension rate of 6 mm/min by using a tensile tester while holding both ends in the longitudinal direction of the measurement sample with a jig; and charting the relationship between the load and the deformation in a stress-strain curve. applying the polyurethane-based adhesive on an AL plate so that the thickness of the sample becomes 4.0 μm; applying an aging treatment, which is leaving the same standing at 60 °C for 6 days; peeling the adhesive layer from the AL plate after aging; preparing a measurement sample by cutting the adhesive layer into a width of 5 mm and a length of 20 mm; applying a tensile load to the measurement sample at a tension rate of 6 mm/min by using a tensile tester while holding both ends in the longitudinal direction of the measurement sample with a jig; and charting the relationship between the load and the deformation in a stress-strain curve. <EOS>