The present invention provides a carbon dioxide separation membrane having a grafted chain into which a substituent having high selective affinity for carbon dioxide is introduced and thus having high carbon dioxide separation capability. The present invention is a method for producing a carbon dioxide separation membrane. This method includes the steps of: (1) irradiating a polymer film with radiation; (2) forming, in the irradiated polymer film, a grafted chain containing a repeating unit of a monomer having a substituent capable of forming a salt with a fluoride ion; and (3) subjecting the substituent capable of forming a salt with a fluoride ion to treatment with a fluoride salt so as to form a salt with a fluoride ion in the substituent.