lcyclohexyl group, a butylcyclohexyl group, an adamantyl group, anethyladamantyl group, or a butyladamantyl group.##STR00087##In formula (xiii), R.sup.1j represents a hydrocarbon group or an oxygen-containing hydrocarbon group; and X.sub.j is a group, formed for example by a (meth)acrylic repeating unit or a norbornene repeating unit, for connecting to a main chain.The hydrocarbon group can be a l