A polymerizable composition for an optical material, comprising: isocyanates having two or more isocyanato groups, which include at least an isophorone diisocyanate; one or more thiols having two or more mercapto groups; an acidic phosphoric acid ester represented by General Formula; wherein, in General Formula, m represents an integer of 1 or 2, n represents an integer of 0 to 18, R 1 represents an alkyl group having 1 to 20 carbon atoms, and R 2 and R 3 each independently represent a hydrogen atom, a methyl group, or an ethyl group; and a tin compound represented by General Formula; wherein, in General Formula, R 4 represents an alkyl group having 1 to 4 carbon atoms, X represents a fluorine atom, a chlorine atom, a bromine atom or -O-C(=O)-R 5 wherein R 5 represents an alkyl group having 1 to 11 carbon atoms, and c represents an integer of 1 to 3, wherein the acidic phosphoric acid ester is contained in an amount of 0.05 parts by weight to 0.9 parts by weight, with respect to a total of 100 parts by weight of the isocyanates and the thiols, the tin compound is contained in such an amount that the content of tin is 0.11 parts by weight to 0.3 parts by weight, with respect to a total of 100 parts by weight of the isocyanates and the thiols, and the thiols include at least one selected from bis(mercaptoethyl)sulfide, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 4,6-bis(mercaptomethylthio)-1,3-dithiane, and 2-(2,2-bis(mercaptomethylthio)ethyl)-1,3-dithiethane. isocyanates having two or more isocyanato groups, which include at least an isophorone diisocyanate; one or more thiols having two or more mercapto groups; an acidic phosphoric acid ester represented by General Formula; wherein, in General Formula, m represents an integer of 1 or 2, n represents an integer of 0 to 18, R 1 represents an alkyl group having 1 to 20 carbon atoms, and R 2 and R 3 each independently represent a hydrogen atom, a methyl group, or an ethyl group; and a tin compound represented by General Formula; wherein, in General Formula, R 4 represents an alkyl group having 1 to 4 carbon atoms, X represents a fluorine atom, a chlorine atom, a bromine atom or -O-C(=O)-R 5 wherein R 5 represents an alkyl group having 1 to 11 carbon atoms, and c represents an integer of 1 to 3, wherein the acidic phosphoric acid ester is contained in an amount of 0.05 parts by weight to 0.9 parts by weight, with respect to a total of 100 parts by weight of the isocyanates and the thiols, the tin compound is contained in such an amount that the content of tin is 0.11 parts by weight to 0.3 parts by weight, with respect to a total of 100 parts by weight of the isocyanates and the thiols, and the thiols include at least one selected from bis(mercaptoethyl)sulfide, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 4,6-bis(mercaptomethylthio)-1,3-dithiane, and 2-(2,2-bis(mercaptomethylthio)ethyl)-1,3-dithiethane. wherein the acidic phosphoric acid ester is contained in an amount of 0.05 parts by weight to 0.9 parts by weight, with respect to a total of 100 parts by weight of the isocyanates and the thiols, the tin compound is contained in such an amount that the content of tin is 0.11 parts by weight to 0.3 parts by weight, with respect to a total of 100 parts by weight of the isocyanates and the thiols, and the thiols include at least one selected from bis(mercaptoethyl)sulfide, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 4,6-bis(mercaptomethylthio)-1,3-dithiane, and 2-(2,2-bis(mercaptomethylthio)ethyl)-1,3-dithiethane.