This invention relates to a rubber composition having excellent workability, fracture characteristics and wear resistance and a low heat buildup and a high storage modulus (G′), and more particularly to a rubber composition comprising not less than 20 parts by mass of a reinforcing filler (B) and 5 to 60 parts by mass of a low-molecular weight aromatic vinyl compound-conjugated diene compound copolymer (C) having an aromatic vinyl compound content of 5 to 80% by mass, a vinyl bond content in a conjugated diene compound portion of 10 to 80% by mass and a weight average molecular weight as measured with a gel permeation chromatography and converted to polystyrene of 5,000 to 300,000 based on 100 parts by mass of a rubber component (A) containing not less than 10% by mass of a modified conjugated diene-based polymer having at least one functional group.