To produce a dilithium initiator in a non-polar solvent without using a polar compound containing one or more nitrogen or oxygen atoms, to obtain a polymer having a narrow mol.wt. distribution by using the obtained solution as such for a polymerization reaction, and further to obtain a polymer containing the 1,2-bond structures of conjugated diene polymer portions in a small amount, when a conjugated diene is used as a monomer.

This method for producing a dilithium initiator comprises reacting an organic monolithium compound with 1,3-diisopropenylbenzene in a molar ratio of 2/1 in a non-polar hydrocarbon solvent. The reaction is carried out in the presence of a π complexed compound having a benzene ring in a π-complexed compound/organic monolithium compound molar ratio of 1/10 to 1,000/1 at a temperature of -20 to 60°C.