NOVELTY - The battery has an exterior body (1) in which a heater layer (15) heats an electric power generation element (4). An aluminum layer (13) consists of a laminate film stacked on the inside while accommodating the electric power generation element. The exterior body contains a polyethylene terephthalate welding layer (16) in each of the inner side surface and the outer side surface. The heater layer is a provided between the welding resin layer on the surface of an outer side, and the metal surface.    USE - Battery e.g. non-aqueous electrolyte batteries, lithium ion battery, and water-system electrolyte batteries such as nickel-hydrogen battery.    ADVANTAGE - Stacks the heater layer on the inner side of the exterior body consisting of a laminate film which suppresses the heater layer from deviating from an exterior body. Enables to efficiently heat the electric power generation element accommodated in the inner side of an exterior body while attaining weight reduction. Provides heater layer easily since heat generating body layer can be formed similarly to another layer by stacking a heater layer on the inner side of the exterior body consisting of a laminate film. Heats the whole electric power generation element uniformly since the heat can be diffused by a thermal-diffusion layer and can be made to disperse to the whole electric power generation element. Suppresses the heat generating body layer and a metal layer from short-circuiting since the heat generating body layer and a metal layer are positioned on both sides of the insulating heat-resistant layer which is hard to soften. Prevents thickness of an exterior body from becoming large to attain size reduction of the battery.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a battery exterior body.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of a layer structure of the exterior body of the battery. (Drawing includes non-English language text).    Exterior body (1)    Electric power generation element (4)    Aluminum layer (13)    Heater layer (15)    Polyethylene terephthalate welding layer (16)