A rubber composition for a tire tread, in which wet grip performance and dry grip performance can be improved without lowering the rolling resistance property, the rubber composition including 5 to 150 parts by weight of silica having 3 to 100 of an average aspect ratio L.sub.1/D between branched particles A-A containing branched particles A on the basis of 100 parts by weight of a rubber component containing a diene rubber, the branched particle A being a particle having contact with at least 3 other particles.