A method for producing a modified conjugated diene polymer includes a modification step (A) that subjects a conjugated diene polymer having a cis-1,4-bond content of 98.5% or more and possessing an active end to a modification reaction to introduce an alkoxysilane compound having two or more reactive groups including an alkoxysilyl group into the active end of the conjugated diene polymer, and a condensation step (B) that subjects the residue of the alkoxysilane compound introduced into the active end to a condensation reaction in the presence of a condensation catalyst that includes at least one element among the elements of the groups 4A, 2B, 3B, 4B, and 5B in the periodic table. The method can produce a modified conjugated diene polymer that exhibits low heat build-up and excellent wear resistance.