Provided is a cell packaging material having a high insulating performance and durability. A cell packaging material comprising a layered body provided with at least a substrate layer, a metal layer, an adhesive layer, and a heat-fusible resin layer in the stated order. The adhesive layer has a resin composition that contains an acid-modified polyolefin and an epoxy resin. In probe displacement amount measurements involving the use of a thermal mechanical analyzer, when a probe is placed on the surface of the adhesive layer at an end part of the cell packaging material and the probe is heated from 40° C. to 220° C., the position of the probe does not drop in relation to the initial value.