There are provided a curable fluorine-containing polymer which can realize a high hardness by photo-curing while maintaining a low refractive index, an antireflection film possessing improved scratch resistance and abrasion resistance while maintaining a reflection reducing effect, and an antireflection-treated article provided with such an antireflection film. The curable fluorine-containing polymer has a number average molecular weight of from 500 to 1,000,000 and is represented by the formula (1): AM (1) in which the structural unit M is a structural unit derived from a fluorine-containing ethylenic monomer and represented by the formula (M): ##STR00001## wherein X.sup.1 and X.sup.2 are the same or different and each is H or F; X.sup.3 is H, F, CH.sub.3 or CF.sub.3; X.sup.4 and X.sup.5 are the same or different and each is H, F or CF.sub.3; Rf is an organic group in which 1 to 3 of Y.sup.1 (Y.sup.1 is a monovalent organic group having 2 to 10 carbon atoms and an ethylenic carbon-carbon double bond at its end) are bonded to a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and ether bond; a is 0 or an integer of from 1 to 3; b and c are the same or different and each is 0 or 1, the structural unit A is a structural unit derived from a monomer copolymerizable with the fluorine-containing ethylenic monomer represented by the formula (M), and the structural unit M and the structural unit A are contained in amounts of from 0.1 to 100% by mole and from 0 to 99.9% by mole, respectively.