A surface treatment agent, which can impart the excellent water- and oil-repellency, soil resistance and feeling to the substrate, is obtained from a fluorine-containing polymer which contains: (A) a monomer which comprises; (A1) a fluorine-containing monomer of the formula: CH2═C(—X)—C(═O)—Y—Z—Rf wherein X is a hydrogen atom, a monovalent organic group, or a halogen atom, Y is —O— or —NH—, Z is a direct bond or a divalent organic group, and Rf is a fluoroalkyl group having 1 to 20 carbon atoms, and (A2) a (meth)acrylate monomer having a cyclic hydrocarbon group, and (B) at least one functional organopolysiloxane selected from the group consisting of a mercapto-functional organopolysiloxane, a vinyl-functional organopolysiloxane, a (meth)acrylamide-functional organopolysiloxane and a (meth)acrylate-functional group.