Provide are a rubber composition which enhances a reinforcing property with a filler and maintains a DRY performance and which has an excellent on-ice performance and a pneumatic tire prepared by using the above rubber composition for a tread. The rubber composition is characterized by having independent air bubbles and comprising (A) a rubber component comprising a natural rubber and an end-modified conjugated diene base polymer, (B) a fine particle-containing organic fiber and (C) a filler.