Transport measurements are performed under the variations of temperature and magnetic field on single crystalline InN nanowires. Conduction at low temperature reveals a three-dimensional Mott variable range hopping mechanism. With rising temperature, a semiconductor-to-metal transition is observed around 80 K. In addition, the nanowire exhibits negative magnetoresistance under both parallel and perpendicular fields due to the suppression of the electron wave function interference. A field direction asymmetry on the change of magnetoresistance is examined, attributing to the conduction channel anisotropy.