Disclosed is a film formation method, including vaporizing a plurality of raw material monomers in respective corresponding vaporizers, supplying the plurality of raw material monomers into a film formation apparatus, causing vapor deposition polymerization of the plurality of raw material monomers in the film formation apparatus to form an organic film on a substrate, and removing an impurity contained in at least one raw material monomer among the plurality of raw material monomers before the vapor deposition polymerization.