NOVELTY - The battery (30) has a negative electrode active material layer (3) placed in opposition to a positive electrode active material layer (2). A polymer electrolyte layer (4) is placed between the positive electrode active material layer and the negative electrode active material layer. A distance defining part i.e. porous sheet, included in the polymer electrolyte layer defines a distance between the positive electrode active material layer and the negative electrode active material layer, where the distance defining part includes resin fibers or resin fabric.    USE - Polymer battery i.e. bipolar lithium ion secondary battery, for use as a power supply for a vehicle.    ADVANTAGE - The distance defining part is included in the polymer electrolyte layer, so that the distance defining part can provide high mechanical strength even if the polymer electrolyte layer is made to be small in thickness, thus strongly enhancing strength of the battery. The distance defining part is placed between the positive electrode active material layer and the negative electrode active material layer, so that smooth ion transfer can be achieved with an improved power output of the battery, thus enabling components to be prevented from being brought into contact with one another and preventing short-circuiting of the polymer electrolyte layer. The battery allows the polymer electrolyte layer to be a solid layer so as to avoid liquid leakage of electrolyte and need of a structure to prevent electrolyte from dissolving, thus enabling the battery to be simplified in structure. The battery utilizes lithium-transition metal composite oxides as positive electrode active material, so that a reaction capability and a cycle durability of the battery can be improved in a cost effective manner while obtaining sufficient battery reaction by achieving ion transfer without any interference due to placement of distance defining parts in adequately spaced locations The battery allows the polymer electrolyte layer to be formed in a thin film configuration with resultant improvement over ion conductivity of the polymer electrolyte layer due to an additional increase in the mechanical strength of the polymer electrolyte layer as a result of distance defining parts, so that the battery with increased efficiency can be obtained.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of a structure of a polymer battery.    Positive electrode active material layer (2)    Negative electrode active material layer (3)    Polymer electrolyte layer (4)    Laminate sheets (5a, 5b)    Polymer battery (30)