CASING MATERIAL FOR POWER STORAGE DEVICE, PRODUCTION METHOD THEREFOR, AND POWER STORAGE DEVICE

A casing material for a power storage device, including a laminate that includes, in order, at least a base material layer, a barrier layer, and a heat-fusible resin layer. The heat-fusible resin layer includes a single layer or a plurality of layers. The heat-fusible resin layer includes at least one layer having a hardness of at least 70 MPa from a cross-section in the lamination direction of the laminate, measured using a nanoindentation method using an indentation load of 100 μN.