To provide a process for producing a desired perfluorinated product at a high yield in a fluorination reaction of a partially fluorinated ester. A perfluorinated compound (4) is obtained by fluorinating in a liquid phase a compound (3) (wherein the fluorine content is at least 30 mass%) obtained by reacting a compound (1) and a compound (2), wherein the compound (1) is HOCH 2 -R A -CH 2 OH, the compound (2) is X 1 C(=O)-C(R B )(R C )(R D ), R A is a bivalent saturated hydrocarbon group or the like which has no hetero atom such as an etheric oxygen atom, X 1 is a halogen atom, and -C(R B )(R C )(R D ) is a branched group.