Crystalline carbon nitride was easily synthesized from CN radicals prepared by the reaction between N atoms and a graphite rod anode in the argon-nitrogen plasma arc at atmospheric pressure. The deposits on Si (111) wafer substrate were identified as beta-C3N4 by the x-ray diffraction method, and the C-N bond was detected in the deposit by infrared (IR) spectroscopy and x-ray photoelectron spectroscopy (XPS). The existence of sp3 orbital on the C atom in C3N4 is presumed from the XPS spectra of the valence band of the deposit.