It is an object of the invention to provide a kind of film build method for the metal oxide film for improving production efficiency and the metal oxide film for obtaining high-quality.Also, the film build method of the present invention implements following processing.In solution container (15), make to be atomized containing the metallic element i.e. material solution of aluminium (14) and obtain material solution mist (M1).In the solution container (25) independently of solution container (15), the reaction assisted solution (24) of the reaction promoter containing aluminum oxide formation is set to be atomized and obtain auxiliary agent mist (M2).Also, via path (L1) and (L2) to nozzle (12) the base feed solution mist (M1) and auxiliary agent mist (M2) being arranged in reaction vessel (11).Then, material solution mist (M1) and auxiliary agent mist (M2) is obtained by mixing mixing fog (M3) in the nozzle (12), to the back side of the P-type silicon substrate (4) in heated condition on supply mixing fog (M3).
