A process for producing a modified conjugated diene polymer includes subjecting an active terminal of a conjugated diene polymer having a vinyl content of less than 10% and a cis-1,4 bond content of 75% or more to a modification reaction with an alkoxysilane compound, and subjecting the alkoxysilane compound (residue) to a condensation reaction in an aqueous solution at a pH of 9 to 14 and a temperature of 85 to 180°C in the presence of a condensation accelerator including a compound containing titanium. The modified conjugated diene polymer exhibits low heat build-up and increased reinforcing properties when used for a rubber composition, and exhibits excellent wear resistance, mechanical characteristics, and processability.