Provided is a water and oil repellent composition that provides water and oil repellency that is excellent for base materials such as textile products, and is excellent for preventing adhesion of polymers on rolls during processing. The present invention involves a method for manufacturing a fluorine-containing polymer comprising a first polymer formed from a first monomer, and a second polymer formed from a second monomer. The manufacturing method includes: (I) a step for obtaining the first polymer by polymerizing the first monomer; and (II) a step for obtaining the second polymer by preparing and polymerizing the second monomer in the presence of the first polymer. The first monomer and/or the second monomer includes a fluorine-containing monomer (a), and both the first monomer and the second monomer include a halogenated olefin (b).