A method for forming a thin film having durability at a low cost is provided. A film formation apparatus 1 is used in the film formation method. The apparatus 1 comprises a vacuum container 11 in which a substrate 100 is placed at a lower part, a vacuum pump 15 for exhaust inside the container 11, a storage container 23 for storing a coating agent 21 provided outside the container 11, and a nozzle having an ejection part 19 capable of ejecting the coating agent 21 at its one end. A solution including two or more kinds of materials is used as the coating agent 21. The solution is ejected to the substrate in an atmosphere at a pressure set based on vapor pressures of respective materials composing the solution.