When a solution sprayed by a spray nozzle portion reaches one surface portion of a substrate, a thin film forming material contained the solution decomposes thermally because the substrate is heated to a prescribed temperature, and a thin film is formed on the one surface portion of the substrate. An imaging section obtains a prescribed information on the thickness of a thin film to be formed on one surface portion of the substrate, and a main control section controls a valve section based on the prescribed information from the imaging section. Since, based on the prescribed information on the thickness of a thin film to be formed on one surface portion of the substrate, the main control section allows the spraying nozzle portion to spray the solution therefrom, a thin film of the desired thickness can be formed with high accuracy.