A magnetically driven carbon shunting arc discharge was generated in nitrogen gas circumstance and amorphous carbon nitride (a-CN_x) films were prepared using plasma-based ion implantation technique. A silicon substrate was immersed into the plasma, and a series of pulse voltage was applied to the substrate synchronizing with an ignition of the shunting arc with a peak current of 2.1 kA. The ambient nitrogen gas pressure was varied from 0.02 to 2 Pa. The shunting arc plasma was successfully produced and was accelerated along carbon rails. Rod heating energy to generate the shunting arc had the minimum value for variation of the ambient gas pressure. A spectroscopic measurement from the plasma light emission showed that the produced plasma contained nitrogen particles in ambient nitrogen gas circumstance. X-ray photoelectron spectroscopy analysis showed that the prepared carbon films contained nitrogen and was obtained to be N/C ratio of 0.35 at 2 Pa nitrogen gas pressure.