The composition for optical materials of the present invention comprises a compound having in one molecule at least one structure represented by the following formula (1): wherein R1, R2, R3, R4, X, Y and n are as defined in the disclosure, an amine compound and an isocyanate compound. Resins obtained by curing the composition by polymerization are useful as well-balanced optical materials having a high impact resistance, a high refractive index and a sufficiently high Abbe's number.