The present invention relates to a composition for optical materials, comprising (a) a compound having in one molecule at least one structure represented by the following Formula 1: ##STR00001## wherein R.sup.1 is a single bond or a C.sub.1-10 hydrocarbon group, each of R.sup.2, R.sup.3 and R.sup.4 is a C.sub.1-10 hydrocarbon group or hydrogen, Y is O, 5, Se or Te, m is 1 to 5, and n is 0 to 5; (b) a compound having in one molecule at least one isocyanate group and/or at least one isothiocyanate group; (c) a compound having in one molecule at least one mercapto group; and (d) an inorganic compound having sulfur atom and/or selenium atom, and also relates to an optical material produced by polymerization curing the composition, a production method thereof, and an optical lens comprising the optical material. The present invention provides a high refractive, high Abbe's number optical material having an improved impact resistance.