There is provided a film forming method of forming a film in a recess formed on a surface of a substrate. The film forming method includes: forming an adsorption-inhibiting region by supplying an adsorption-inhibiting gas to the substrate; adsorbing a silicon-containing gas to a region other than the adsorption-inhibiting region by supplying the silicon-containing gas to the substrate; and forming a silicon nitride film by exposing the substrate to a nitrogen-containing gas so that the nitrogen-containing gas reacts with the adsorbed silicon-containing gas, wherein the adsorbing the silicon-containing gas includes controlling a dose amount of the silicon-containing gas to be supplied to be equal to or greater than an adsorption saturation amount of the silicon-containing gas to be adsorbed on the substrate on which no adsorption-inhibiting region is formed.