An aqueous dispersion of a fluorine-containing copolymer comprising, as copolymerization units, (A) a (meth)acrylate represented by [CH2═CHRCOO(NH)rR1NR2R3R4]+Y−, (B) a perfluoroalkylalkyl(meth)acrylate represented by CmF2m+1CpH2p(NR′SO2)qOCOCR═CH2 or a polyfluoroalkylalkyl(meth)acrylate thereof, or a polyfluoroalkyl(meth)acrylate represented by CnF2n+1(CH2CF2)a(CF2CF2)b(CH2CH2)cOCOCR═CH2, (C) benzyl(meth)acrylate, (D) a fluorine-free polymerizable monomer other than components (A) and (C), and (E) a crosslinkable group-containing polymerizable monomer. The aqueous dispersion can improve the dispersion stability of an aqueous dispersion of a water- and oil-repellent when used as a water- and oil-repellent comprising the fluorine-containing copolymer as an active component.