This manuscript reports on the structure, bonding states of nitric amorphous carbon (a-CNx) films and its correlation with electrical, optical properties with post-annealing treatment. a-CNx films were deposited on Si(100) by reactive rf magnetron sputtering using a gas mixture of Ar and N-2. X-ray photoelectron spectroscopy revealed that there are two different C-N bonding states where N is bonded to both sp(2) and sp(3) C atoms. The amount of N-sp(3) C bond is proportional to the N/C atomic ratio in a-CNx. As the amount of N-sp(3) C bond decreased with annealing, total sp(3)/sp(2) bond ratio, resistivity, density and refractive index also decreased. Compared to amorphous carbon (a-C), a slow decrease tendency of total sp(3)/sp(2) bond ratio was observed in a-CNx due to thermal resistance of the N-sp(3) C bond.