A composition comprising a fullerene-containing polymer obtained by reacting a polymer prepared by living radical polymerization with a fullerene, wherein: (a) the living radical polymerization is carried out using a monomer, a polymerization initiator, transition metal catalyst and a ligand capable of reversibly forming a complex with the transition metal catalyst, (b) the polymer comprises at least one of a first repeat unit including a moiety having charge transport ability and a second repeat unit including a moiety having non-linear-optical ability, and (c) the composition exhibits photorefractive ability.