A fluorine-containing surface active composition capable reducing the surface tension of water to the interfacial tension between water and oil, which comprises (A) at least one of cationic, non-ionic and ampho-ionic surfactant showing a surface tension of not more than 25 dyne/cm when determined on a 0.01 to 1.0 % by weight aqueous solution and having at least one fluorine-containing group comprising not less than 6 carbon atoms, of which each carbon atom bears at least one fluorine atom, and (B) at least one of surfactants of the formula: ##STR1## wherein R is a substituted or unsubstituted aliphatic group of 4 to 20 carbon atoms or a substituted or unsubstituted aromatic hydrocarbon group of 6 to 20 carbon atoms, R.sup.1, R.sup.2 and R.sup.3 are each a hydrogen atom, a substituted or unsubstituted aliphatic group of 4 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group of 6 to 20 carbon atoms or a fluorine-containing group comprising not more than 5 carbon atoms, of which each carbon atom bears at least one fluorine atom, and X.sup.- is an anion, provided that at least one of R.sup.1, R.sup.2 and R.sup.3 is a fluorine-containing group or, when none of R.sup.1, R.sup.2 and R.sup.3 is a fluorine-containing group, X.sup.- is an anion corresponding to the fluorine-containing group.