To provide a rubber composition which has improved in heat resistance and is suitable as the reinforcing rubber for the side wall portion of a tire and the bead filler rubber of a tire, and a pneumatic tire using the same.

The rubber composition comprises (A) natural rubber and/or a diene based synthetic rubber and (B) a compound represented by the formula: R1-S-S-A-S-S-R2, wherein A is a 2-10C alkylene group; and R1 and R2 are each a monovalent organic group containing a nitrogen atom, and the pneumatic tire uses this rubber composition in the rubber reinforcing layer of the side wall portion and/or in the bead filler.