An antifouling coating composition comprising (A) a silyl ester copolymer containing constituent units derived from a polymerizable unsaturated carboxylic acid silyl ester; (B) a carboxylic acid; (C) a bivalent or trivalent metal compound; and (D) a dehydrating agent. It is preferred that the component (C) be contained in an amount of 1.2 equivalents or more, in terms of the number of equivalents of metal as a constituent of the component (C), per equivalent of carboxyl group of the carboxylic acid (B); that the component (C) be a bivalent metal compound; and that the component (C) be a compound of at least one metal selected from the group consisting of zinc, copper, magnesium, calcium and barium. From the antifouling coating composition, there can be obtained an antifouling coating film which exhibits less cracking tendency, excellent adherence so as to ensure less peeling tendency and desirably controlled hydrolysis rate so as to be excellent in antifouling performance, in particular, antifouling properties in highly fouling environment and long-term antifouling properties. With respect to the provided antifouling coating composition, its storage stability is high, its concentration can be increased, the amount of solvent used therefor can be reduced, and its applicability is high.