There is provided a modified conjugated diene-based polymer having a silyl group substituted with one or more alkoxy groups, and one or more nitrogen atoms on the chain ends of a conjugated diene-based polymer, the modified conjugated diene-based polymer being obtained by polymerizing a conjugated diene compound, or copolymerizing a conjugated diene compound with an aromatic vinyl compound, by using a polyfunctional anionic polymerization initiator prepared from a polyvinyl aromatic compound and an organolithium compound in a range of a molar ratio (the polyvinyl aromatic compound/the organolithium compound) of from 0.05 to 1.0, so as to obtain the conjugated diene-based polymer, and by reacting a living polymer end of the conjugated diene polymer with the compound having a silyl group substituted with two or more alkoxy groups, and one or more nitrogen atoms.