The present invention provides a tread rubber composition for a tire, which highly controls energy loss in a wide frequency range and has high frictional force especially on wet road surfaces, and a tire using the same. Specifically, the present invention provides a rubber composition for a tire comprising 5 to 100 parts by weight of a fatty acid obtained from a vegetable oil having an iodine value of at least 80, based on 100 parts by weight of a rubber component, wherein the ratio of tan.delta. at 60.degree. C. to tan.delta. at 0.degree. C. is at least 0.85, and a pneumatic tire using the rubber composition.