[PROBLEM TO BE SOLVED] To provide an organopolysiloxane paint composition capable of forming an antifouling coating film having an excellent long-term antifouling property.[SOLUTION] A curable composition obtained by mixing: (A) 100 parts by weight of a reaction curable silicone rubber with: (B) 1 to 100 parts by weight of an organopolysiloxane mixture including a product obtained by an R.sup.2OH elimination reaction of: (B1) an organopolysiloxane represented by: (R.sup.2O)((R.sup.2O).sub.2SiO).sub.n-1Si(OR.sup.2).sub.3 wherein n is an integer of 2 or more and R.sup.2 each is independently a monovalent hydrocarbon group, and (B2) an organopolysiloxane having at least one structure represented by: .ident.SiR.sup.3OH wherein R.sup.3 is a divalent hydrocarbon group, in a molecule.