In a preliminary deposition for producing an optical film in which multilayered optical thin-film is formed on a film substrate, a plurality of sputtering chambers are simultaneously energized to deposit a stacked body of thin-films made of two or more different materials on the film substrate, and the thicknesses of the plurality of thin-films are calculated from the optical properties obtained by the optical measuring unit (80) equipped in a sputtering apparatus. Measurement of the thicknesses and adjusting the deposition conditions for thin-films are repeated until the optical properties obtained by the optical measurement unit or the thickness of the respective thin-films calculated from the optical properties falls within a prescribed range.