A method for producing a modified conjugated diene-based polymer including a polymerization step of obtaining a conjugated diene-based polymer having an active end by use of a polymerization initiator containing a compound having at least one nitrogen atom in a molecule and an organic lithium compound; and a modification step of reacting a modifier represented by the following chemical formula (6) with the active end of the conjugated diene-based polymer: wherein R4 to R7 each independently represent an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms; R8 represents an alkylene group having 3 to 10 carbon atoms; R9 represents an alkylene group having 1 to 20 carbon atoms; m is an integer of 1 or 2; and n is an integer of 2 or 3.