Tensile strength and creep behavior of a carbon-carbon composite (C/C) reinforced with a high modulus type PAN based carbon fiber (C/C (M40)) and a C/C reinforced with a low modulus type carbon fiber (C/C (T300)) were examined from room temperature to 2773 K in an inert atmosphere. Tensile strength of both C/Cs at the elevated temperatures enhanced up to 2273 K. Over 2273 K, tensile strength of the C/C (M40) continued to increase, on the other hand, tensile strength of C/C (T300) degraded. Tensile strength of C/C (T300) could not be obtained at 2773 K due to the decline of applied stress during tensile test by rapid creep deformation. Creep deformation appeared from 1873 K in both C/Cs regardless to the types of the reinforcing carbon fibers. No variation was found in the activation energy, however, C/C reinforced with a higher modulus carbon fiber exhibited lower stress exponent. The creep resistance of C/Cs could be enhanced by a carbon fiber processed at higher heat treatment temperature. The heat treatment of a C/C itself also enhanced creep resistance, however, its effect could not reach to that from the heat treatment of a carbon fiber.