A
conjugated diene polymer is provided that comprises a
conjugated diene-based constituent unit and a constituent unit of formula (I) below, at least one terminus of the
polymer being modified by a compound of formula (II):X1, X2, and X3 independently denote a group of formula (Ia) below, a
hydroxy group, a hydrocarbyl group, or a substituted hydrocarbyl group, and at least one of X1, X2, and X3 is a group of formula (Ia) below or a
hydroxy group.wherein R1 and R2 independently denote a hydrocarbyl group having 1 to 6 carbon atoms, a substituted hydrocarbyl group having 1 to 6 carbon atoms, a silyl group, or a substituted silyl group, and R1 and R2 may be bonded so as to form, together with the
nitrogen atom, a ring structure,wherein n denotes an integer of 1 to 10, R3 denotes a
hydrogen atom, a hydrocarbyl group having 1 to 6 carbon atoms, or a substituted hydrocarbyl group having 1 to 6 carbon atoms, A1 denotes an
oxygen atom or an —NR4— group, wherein R4 denotes a
hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, and A2 denotes a
nitrogen atom- and / or
oxygen atom-containing functional group.