A heat-sealable insulating film for installation in a secondary battery including a positive electrode member and a negative electrode member being formed from a collector foil and an active material layer formed to cover one end on the collector foil, wherein an adhesive layer is adhered by heat-sealing to cover at least a boundary of an exposed part of the collector foil and the active material layer of the positive electrode member or the negative electrode member, a peripheral edge of the positive electrode member or the negative electrode member has a cross-sectional surface including the collector foil and the insulating film, and the insulating film consists of at least two layers of a base material layer made of a polyolefin resin and the adhesive layer made of a polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof