PROBLEM TO BE SOLVED: To improve efficiency in the use of a material gas in film formation.SOLUTION: In a deposition apparatus, a material gas Gs is supplied in an internal space in a housing chamber 100 for housing a substrate from a lateral of the substrate along an X direction by using a material gas supply part, and a first block gas Gb1 is supplied obliquely downward along the X direction to a position on an upstream side in the X direction from the substrate and on a downstream side in the X direction from a supply duct 210. By doing this, the material gas Gs is pressed by the first block gas Gb1 at a position on the upstream side in the X direction from the substrate thereby to inhibit diffusion of the material gas Gs before reaching the substrate.
