To obtain the subject composition useful for a nonlinear optical and EO materials, by including a stilbene derivative containing a specific structural unit.

This composition uses a stilbene derivative having a structural unit of formula I (X2 is H, CH3, CH2CH3, etc.; Y is H, F or CH3; R1 and R2 are each H, CN, a halogen, etc.; R3 and R4 are each H, a halogen, an alkyl, a fluoroalkyl, etc.; Z is H, OH, SR3, SO2R3, etc.), (n) and (m) are each 1-20; these coloring groups are embedded in a polymer, bonded as a side chain by covalent bond and provided to the interior of a main chain back bone) such as 4-aminophenyl-4'-(6-hydroxyhexylsulfonyl)stilbene, etc. Preferably a composition containing a repeating monomer unit of formula II [A is CX2, etc.; X is H, F, etc.; B is (C6F4)n ((n) is 1-10), etc.; Y is O, S, P, etc.; G is H, benzene, biphenyl, etc.; D is H, OH, NO2, etc.; Z is H, F, etc.; E is O or S; F is H or a fluorinated aromatic group] is used.