PROCESS FOR PRODUCING BLOCK COPOLYMER

A process for producing a block copolymer of a conjugated diene and a polar monomer, which comprises : polymerizing a conjugated diene alone in the presence of a catalyst composition comprising (A) a metallocene complex comprising a rare earth metal compound and (B) an ionic compound comprising a non-coordinating anion and a cation and/or an aluminoxane; and then adding a polar monomer to produce the target block copolymer.