A method for producing a gas separation membrane containing fine particles uniformly dispersed in a resin, including the following (A) and (B): (A) a step of mixing the fine particles with a matrix resin, the amount of the fine particles with respect to the entire mass of the mixture being adjusted to 1 mass % to 50 mass %, to thereby prepare a master batch; and (B) a step including dissolving the master batch in a solvent, applying the prepared solution onto a substrate, and evaporating the solvent.