PURPOSE: To obtain the title composition which can allow an antifouling agent incorporated into a coating material to be stably released over a long period of time and gives a firm coating film capable of retaining a proper degree of solubility in water, by using a resin capable of slowly dissolving in seawater.

CONSTITUTION: The title composition contains as the essential film-forming component a polyurethane resin having a metal salt bond consisting of, for example, a specified metal and a carboxyl group or an acid radical represented by a group containing phosphrus atom(s) or sulfur atom(s), i.e., a bond comprising a polyvalent metal salt, in the principal chain and/or at the terminal.