The present invention relates to a rubber composition containing carbon black for blending with rubber which is obtained in a reaction equipment comprising a combustion gas-generating zone, a reaction zone and a reaction-stopping zone by producing a high temperature combustion gas in the combustion gas-generating zone, subsequently spraying and introducing a raw material into the reaction zone to form a reaction gas stream containing carbon black and then quenching the above reaction gas stream by a multistage quenching medium-introducing means to terminate the reaction, wherein (1) the above carbon black for blending with rubber satisfies the following relational equations (1) and (2): 10