An antifouling paint composition containing, as a vehicle component, a resin obtained by grafting a hydrolyzable polyester (A) having (a) an oxyacid and/or its condensate, (b) a polybasic carboxylic acid containing no hydroxyl group and/or its acid anhydride and (c) a polyhydric alcohol reacted so that the equivalent ratio of the total hydroxyl groups in (a) and (c) to the total carboxyl groups in (a) and (b) is from 1/0.9 to 1/1.1, to a vinyl copolymer (B') containing, as a constituting component, at least 10 mol% of a polymerizable unsaturated monomer having a functional group reactive with a hydroxyl group in (A), said resin having free carboxyl groups blocked by a blocking agent so that the acid value is not higher than 20.