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. A first heat-fusible resin layer, among the heat-fusible resin layers, that constitutes the surface of the laminate has a logarithmic decrement ΔE of no more than 0.20 in a rigid body pendulum measurement at 140° C.