To provide a modified polymer which exhibits high interactions with carbon black and silica, when used for rubber compositions containing the carbon black and/or silica, and has excellent low exothermic property, breakability and abrasion resistance, to provide a rubber composition using the modified polymer, and to provide a tire using the modified polymer.

This modified polymer obtained by reacting a compound represented by general formula (1) [A1or A2is N or C-R13; R1, R2and R13are H or a hydrocarbon group; R3or R4is a hydrocarbon group; X1is a hydrocarbon group; wherein the groups each may contain an ether structure, a thioether structure, hydroxy group, thiol group and their alkali metal compounds, alkaline earth metal compounds or alkylsilyl compounds; (n) is an integer of 1 to 3] or the like with an active metal site-having polymer. A rubber composition, especially a tire, using the modified polymer.

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