To provide a method for preparation of a salt used for an acid generator etc., in a resist composition.

The salt represented by formula (I) [wherein, Q¹ and Q² represent each a fluorine atom or a 1-6C perfluoroalkyl group, Y represents a 1-18C hydrocarbon group which may have a substituted group, and Z⁺ represents an organic cation] is prepared by reacting a compound represented by formula (II) (Q¹, Q² and Y represent each the same in the above ), a salt represented by formula (III) [wherein Z⁺ represents an organic cation, and X^-represents an anion] and water in the presence of an organic base.