A negative-electrode active material layer having an uneven pattern is formed on a surface of a copper foil as a negative-electrode current collector by applying an application liquid by a nozzle-scan coating method. Subsequently, an application liquid containing a polymer electrolyte material is applied by a spin coating method, thereby forming a solid electrolyte layer in conformity with the uneven pattern. Subsequently, an application liquid is applied by a doctor blade method, thereby forming a positive-electrode active material layer whose lower surface conforms to the unevenness and whose upper surface is substantially flat. A thin and high-performance all-solid-state battery can be produced by laminating an aluminum foil as a positive-electrode current collector before the application liquid is cured.