Carbon nitride (CN,) thin films were synthesized by ion beam assisted deposition (IBAD) with electron beam evaporation of C and simultaneous irradiation of N ion beams. The (111)- and (200)-oriented TiN thin films and Si (100) wafer were used for substrates. The N/C content ratios of CN, films were determined to be up to 0.44. The friction coefficients against SiC and steel balls were 0.2-0.3, irrespective of the substrate materials, in both air and a vacuum of 1.3 x 10(-4) Pa. The films prepared with a N/C transport ratio of one on the TiN(200) substrate showed good wear resistance in comparison with those prepared on the Si substrate. The wear rate of this sample was 0.25 times lower than that of a-C:H films. The difference in this wear behavior was attributed to higher adhesive strength due to the chemical bonding between the film and the TiN substrate.