To provide a perfluorocarboxylic acid salt excellent in a surface tension reducing ability. A perfluorocarboxylic acid salt having an iron content of at most 10 ppm by mass and represented by the following formula (1): R.sup.F(OCF(X.sup.1)CF.sub.2).sub.k-1OCF(X.sup.2)COO.sup.-M.sup.+ (1) wherein R.sup.F is a C.sub.1-10 monovalent perfluorinated organic group, each of X.sup.1 and X.sup.2 is independently a fluorine atom or a trifluoromethyl group, k is an integer of at least 1, and M.sup.+ is an ammonium ion or an alkyl-substituted ammonium ion.