Electrospun carbon nanofibers (ECNs) were prepared through stabilization and carbonization of electrospun polyacrylonitrile nanofibers as the precursor, and their morphological, structural, and electrical properties were evaluated. Temperature dependencies of resistivity of ECNs carbonized at several temperatures were investigated. The character of the temperature dependencies of resistivity was typical for semiconducting materials. The values of corresponding activation energies were obtained for ECN samples carbonized at different temperatures, and the results showed that the activation energy of ECNs decreased with the increase of carbonization temperature.