Disclosed is a polymerizable composition for optical materials containing (a) an aromatic isocyanate, (b) a mercapto group-containing compound, and (c) a phosphorus-containing compound represented by the following general formula (1). O = P n - X 3 (wherein n represents an integer of 0 or 1. X represents a substituted or unsubstituted straight or branched alkyl group having 1 to 6 carbon atoms or the like. In the case where X is a substituted group, the substituted group represents a halogen atom or the like.)