A laminate to be served as seal film for sealing the electrolyte of battery or as protection film for protecting the electrode part of battery, comprising a metal layer, a surface-treated layer formed over the surface of the metal layer and a layer of an adhesive resin of a polyolefin modified by carboxyl group or a group derived therefrom formed over the said surface-treated layer, which laminate is superior in the adhesive strength between the metal layer and the adhesive resin layer and in the fastness to organic polar solvents or to salts and, therefore, does not suffer from occurrence of interlayer separation on contacting with a non-aqueous solvent and, hence, can favorably be used in particular as seal film for sealing the electrolyte of secondary battery.