Rubber composition and tire Modified Polymer

A rubber composition modified polymer and tires is an object of the present invention is to provide a modified polymer to which a rubber composition having a particularly low heat generation and excellent productivity, a rubber composition, the modified polymer-containing and by using the rubber composition produced tire can be realized. The modified polymer of the present invention is obtained by reacting a modifier having a nitro group and a carboxy group, with a conjugated diene polymer containing no tetra-substituted olefin and / or tri-substituted olefin.