Disclosed is a resin composition which is characterized in that the metal content in the composition is not more than 1000 ppm. The resin composition contains a copolymer which is obtained by copolymerizing 80-99.9 parts by weight of a vinyl monomer mainly containing a (meth)acrylic acid alkyl ester and 0.1-20 parts by weight of a vinyl monomer having a reactive functional group by living radicalpolymerization, while using, as a polymerization initiator, one of the following: (a) an organic tellurium compound represented by the formula (1) below; (b) a mixture of an organic tellurium compound represented by the formula (1) below and an azo polymerization initiator; (c) a mixture of an organic tellurium compound represented by the formula (1) below and an organic ditellurium compound represented by the formula (2) below; and (d) a mixture of an organic tellurium compound represented by the formula (1) below, an azo polymerization initiator and an organic ditellurium compound represented by the formula (2) below. (In the formula, R<1> represents a C1-C8 alkyl group, an aryl group, a substituted aryl group or an aromatic heterocyclic group; R<2> and R<3> respectively represent a hydrogen atom or a C1-C8 alkyl group; and R<4> represents an aryl group, a substituted aryl group, an aromatic heterocyclic group, an acyl group, an amide group, an oxycarbonyl group or a cyano group.) (R<1>Te)2 (2) (In the formula, R<1> is as defined above).