Power storage device packaging material and method for manufacturing power storage device packaging material

A method for manufacturing a power storage device packaging material, the method comprising:

• adhering a substrate layer to one surface of a metal foil layer via an adhesive layer;
• forming a substrate protective layer on a surface of the substrate layer on the opposite side of the adhesive layer;
• and
• forming a sealant layer on a surface of the metal foil layer on the opposite side of the adhesive layer via a sealant adhesive layer,
• wherein the substrate protective layer is a cured product of a raw material containing a polyester resin and a polyisocyanate compound, has a glass transition temperature (Tg) of 100 to 140° C., and has a thickness of 1 to 5 μm, with a ratio of the thickness of the substrate protective layer to a thickness of the substrate layer being 35% or less.