The present invention provides a rubber composition that improves processability and fuel efficiency without decreasing mechanical strength and abrasion resistance, which are excellent properties of natural rubber, and a pneumatic tire using the rubber composition for a tire tread. Specifically, the present invention provides a rubber composition for a tire tread comprising 5 to 150 parts by weight of silica having nitrogen-adsorbing specific surface area of 100 to 300 m2/g and/or 5 to 150 parts by weight of carbon black having nitrogen-adsorbing specific surface area of at least 70 m2/g and dibutyl phthalate oil absorption of at least 70 ml/100 g, based on 100 parts of a rubber component containing 5 to 100% by weight of a deproteinized natural rubber having a weight average molecular weight of 1,400,000 and nitrogen content of at most 0.1% by weight, and a pneumatic tire comprising the rubber composition for a tire tread.