RUBBER COMPOSITION AND PNEUMATIC TIRE

An object of the present invention is to provide a rubber composition which can further improve abrasion resistance without deterioration in energy efficiency, and a pneumatic tire using the rubber composition. The rubber composition comprises a polymer mixture obtained by modifying a polymer composed of at least one of a conjugated diene compound and an aromatic vinyl compound with a compound having at least one of an ester group and a carboxyl group; at least one of tetraamines; and silica, the polymer mixture having a weight-average molecular weight of 1.0×10to 1.0×10, and the tetraamines being a compound represented by the following formula (I): wherein each of R, R, R, R, R, R, Rand Rindependently represents a hydrogen atom or an alkyl group, and ALK represents a tetravalent aliphatic hydrocarbon group.