The present invention provides a novel compound for optical materials, and a curable composition, a cured body and an optical article containing the compound for optical materials. According to an embodiment, there is provided a compound for optical materials represented by Formula (Ia) below: ##STR00001##
In Formula (Ia), X.sup.1 and X.sup.2 are each NH, S, or O. R.sup.1 is a 1- to 30-valent organic residue. R.sup.3 is a group composed of a polymer having a repeating unit selected from the group consisting of (CH.sub.2).sub.mO, (CH.sub.2CH.sub.2O), (CH(CH.sub.3)CH.sub.2O), (CH.sub.2CH(CH.sub.3)O), (C(O)CH.sub.2CH.sub.2CH.sub.2CH.sub.2CH.sub.2O), (C(O)OCH.sub.2CH.sub.2CH.sub.2CH.sub.2CH.sub.2O), and (C(O)OCH.sub.2CH.sub.2CH.sub.2CH.sub.2CH.sub.2CH.sub.2O), a random copolymer having at least two repeating units selected from the group, or a block copolymer having at least two repeating units selected from the group.