PURPOSE: A polymer having water repellency and dry-soil resistance and being useful as a water repellent or a stain-proofing agent, prepared by (co)polymerizing an α-polyfluoroalkyl acrylate (derivative) alone or with other double bond- containing polymerizable monomers.

CONSTITUTION: A homopolymer of an α-polyfluoroalkyl acrylate (derivative) represented by formulaI[wherein Rf is a 3W21C perfluoroalkyl and Y is a carboxyl group or a group derived therefrom (e.g., groups of formulas II and III or CN, R is a 1W10C alkyl, R' and R" are each H or a 1W10C alkyl)], i.e., a polymer having structural units of formula IV (wherein R1 and Y are each defined as above), or a copolymer of a monomer of formulaIand other double bond-containing polymerizable monomers. This (co)polymer exhibits water repellency equal to that of a polymer of a known polyfluoroalkyl acrylate and besides it has dry-soil resistance. Accordingly, it is extremely effective as a water repellent or a stain-proofing agent.