An object of the present invention is to extend the catalyst lifetime in a method for producing fluoromethane by pyrolyzing fluorine-containing methyl ether in the presence of a catalyst. The present invention provides a method for producing fluoromethane by pyrolyzing a fluorine-containing methyl ether represented by Formula (1) in a gas phase in the presence of a catalyst, the pyrolysis being conducted at a moisture concentration of 100 ppm or less, wherein R1 and R2 are identical or different, and each represents a substituted or unsubstituted straight or branched monovalent aliphatic hydrocarbon group, substituted or unsubstituted monovalent aromatic hydrocarbon group, substituted or unsubstituted monovalent cyclic aliphatic hydrocarbon group, hydrogen atom, or halogen atom.