Presented is battery packaging material which is made of a laminate including, as the essentials, a base material layer, a metal layer and a sealant layer in this order. When a product obtained by packaging a battery element with the packaging material in a hermetically sealed state through heat sealing is heated, the packaging material delaminates at least at a part of the interface between the metal layer and the outside surface of the sealant layer with the hermetically sealed state being kept, and thereafter works so as to make the product unsealed.