METHOD FOR PRODUCING MODIFIED CONJUGATED DIENE POLYMER, POLYMER COMPOSITION, CROSSLINKED POLYMER AND TIRE

A modified conjugated diene copolymer, which is obtained by modifying a conjugated diene polymer that has been obtained by polymerizing a conjugated diene compound or by polymerizing a conjugated diene compound and an aromatic vinyl compound, is produced by a production method which comprises a first modification step wherein an unsaturated binding site in the skeleton and/or in a side chain of the conjugated diene polymer is reacted with a first compound that contains a group 4 or group 13 element of the periodic table.