A gel electrolyte battery in which adhesion between a layer of an active material of an electrode and a gel electrolyte is raised to provide for sufficient mobility of lithium ions, and a method for the preparation of the gel electrolyte battery. The gel electrolyte battery is comprised of a battery device accommodated in an exterior material of a laminated film and sealed in it on heat fusion. The method for the preparation of the gel electrolyte battery includes a battery device preparation step of layering a positive electrode and a negative electrode via a gel electrolyte to form the battery device, an accommodating step of accommodating the battery device from the battery device preparation step in the laminated film, and a heating step of heating the battery device, accommodated in the laminated film in the accommodating step, under a pressured state.