Abstract: Provided are a rubber composition which is improved in dispersion of silica into a rubber composition and improved in both of a low heat build-up and abrasion resistance and which is suitable as a tire tread member and a tire prepared by using the same. In a rubber composition compounded with precipitated silica, a cetyltrimethylammonium bromide-adsorbing specific surface area (CTAB) (m2/g) and the mode Aac (mm) in diameters of primary aggregates determined by acoustic measurement of particle size distribution satisfy equation (I) shown below: Aac??0.76×(CTAB)+274 and further an ignition loss (mass reduction % when heated at 750° C. for 3 hours) and a heating loss (mass reduction % when heated at 105° C.