Provided is a water- and oil-repellent agent composition that is capable of producing an article having a high water pressure resistance and a low water absorption rate. The water- and oil-repellent agent composition contains a fluorine-containing polymer having a unit based on a monomer (a), a unit based on a monomer (b1), a unit based on a monomer (b2), a unit based on a monomer (b3), and a unit based on a monomer (c), wherein relative to all the units that constitute the fluorine-containing polymer, the proportion of the unit based on the monomer (a) is from 70 to 80% by mass, the proportion of the combination of the unit based on the monomer (b1), the unit based on the monomer (b2) and the unit based on the monomer (b3) is from 12 to 28% by mass, and the proportion of the unit based on the monomer (c) is from 2 to 8% by mass. Monomer (a): a compound represented by (Z-Q)nX. Monomer (b1): a monomer not having a polyfluoroalkyl group (Rf group), but having an alkyl group of 22 carbon atoms. Monomer (b2): a monomer not having an Rf group, but having an alkyl group of 20 carbon atoms. Monomer (b3): a monomer not having an Rf group, but having an alkyl group of 18 carbon atoms. Monomer (c): a halogenated olefin.