METHOD FOR PRODUCING MODIFIED CONJUGATED DIENE-BASED POLYMER, MODIFIED CONJUGATED DIENE-BASED POLYMER, POLYMER COMPOSITION, CROSSLINKED BODY, TIRE AND COMPOUND

A modified conjugated diene-based polymer having high Mooney viscosity and good shape stability and exhibiting excellent processability and low heat build-up is obtained in as few steps as possible. The modified conjugated diene-based polymer is produced by a method of reacting a conjugated diene-based polymer having an active chain end, obtained by polymerizing a monomer containing a conjugated diene compound in the presence of an initiator that contains at least either of an alkali metal compound and an alkaline earth metal compound, with a compound [M] having at least two groups selected from the group consisting of a group “—C(R)N-A” and a group “—N═C(R)-A”, where Ris a hydrogen atom or a hydrocarbyl group and Ais a monovalent group having an alkoxysilyl group.