PURPOSE: To provide an antifouling coating compsn. having no toxicity which can provide a coating film capable of exhibiting an antifouling effect for a long period of time, by combining a homopolymer of a specific silicon-containing acrylic monomer or a copolymer of said monomer with a copolymerizable vinyl monomer with a water repellent.

CONSTITUTION: A homopolymer or a copolymer is prepd. from a silicon- containing acrylic monomer of formula I (wherein R1 is H or methyl; R2 is 1W6C bivalent hydrocarbon group; and n is 3W200) or a combination of said monomer with a copolymerizable vinyl monomer, e.g., of formula II (wherein Rf is a monovalent org. residue contg. linear or branched perfluoroalkyl). The (co)polymer is combined with a water repellent (e.g., silicone oil or liquid paraffin) to prepare the desired antifouling coating compsn. Constructions and instruments such as ships or fishing nets are coated with the antifouling coating compsn. to be prevented from undergoing epiphytical growth thereon of marine lives.