A film forming method of forming a film on a substrate by using a film forming apparatus including a processing container, and a stage provided in an interior of the processing container to place the substrate thereon and in which aluminum is contained, includes: forming a film continuously on one substrate or on a plurality of substrates by supplying a gas for film formation to the interior of the processing container while heating the substrate placed on the stage; cleaning the interior of the processing container with a fluorine-containing gas in a state in which the substrate is unloaded from the processing container; and performing a post-process by generating plasma of an oxygen- and hydrogen-containing-gas in the interior of the processing container, wherein the forming the film, the cleaning the interior of the processing container, and the performing the post-process are repeatedly performed.