The optical element of the present invention has a first member and a second member which have been joined in close contact, and has n.sub.d1>n.sub.d2 and (n.sub.F1-n.sub.C1)<(n.sub.F2-n.sub.C2), where the first member is formed of a resin having both a benzene ring and a fluorine atom, or the second member is formed of a resin having an alicyclic structure It also makes use of an optic-purpose resin precursor composition prepared by mixing a first resin precursor having n.sub.d<1.50 and (n.sub.F-n.sub.C)>0.003 in an uncured state and a second resin precursor having n.sub.d<1.62 and (n.sub.F-n.sub.C)>0.010.