A rubber composition from which a vulcanized rubber suitable for producing, for example, a pneumatic tire having excellent abrasion resistance, breaking strength, rolling resistance, wet skid resistance, and the like can be prepared. The rubber composition comprises a rubber component (A) comprising a diene rubber comprising 20 mass % or more of a modified styrene-butadiene copolymer (a1) and 5 mass % or more of a modified conjugated diene polymer (b1), and a filler (B), wherein the modified conjugated diene polymer (b1) is a conjugated diene polymer obtained by modifying the active terminals of a conjugated diene polymer having a cis-1,4 bond content of 80% or higher, with an alkoxysilane compound, and the filler (B) comprises at least either of 2 to 100 mass parts, relative to 100 mass parts of the rubber component (A), of carbon black (b1) and 30 to 100 mass parts, relative to 100 mass parts of the rubber component (A), of silica (b2).