Abstract: An antifouling coating composition can inhibit or prevent fouling of hulls of ships and other underwater structures. The coating composition includes (A) an antifouling agent, (B) a film-forming copolymer having a number average molecular weight of 1,000 to 50,000, and structural units derived from a trialkylsilyl ester of polymerizable unsaturated carboxylic acid in an amount of 20 to 65% by weight, based on the copolymer, and (C) chlorinated paraffin having 8 to 30 carbon atoms, number average molecular weight of 200 to 1200 and a chlorination ratio of from 35 to 75% by weight. Zinc flower may also be included in the antifouling coating composition in place of or in addition to the antifouling agent (A).