Disclosed is a method for producing a modified conjugated diene polymer which enables to obtain a modified conjugated diene polymer which is excellent in low heat generation property and wear resistance. This method for producing a modified conjugated diene polymer comprises a modification step (A) wherein a conjugated diene polymer having a cis-1,4-bond content of not less than 98.5% and an active end is used, and an alkoxysilane compound having two or more reactive groups including an alkoxysilyl group is introduced into the active end of the conjugated diene polymer, and a condensation step (B) wherein the residue of the alkoxysilane compound introduced in the active end is condensed in the presence of a condensation catalyst containing at least one element selected from group 4A, 2B, 3B, 4B and 5B elements of the periodic table.