The mechanical properties of CrCN films on SUS304 substrate have been studied. CrCN films were prepared by the reactive ion beam mixing method. In this method, N2+ ion irradiation and Cr evaporation were simultaneously carried out in a CH4 gas atmosphere. N2+ ions were accelerated at an energy of 10 keV, and the ion beam current densities were changed from 10 to 60 μA/cm2.Atomic concentration, chemical state and microstructure of the films were investigated by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The mechanical properties such as hardness and wear resistance were determined using Knoop hardness tester and pin-on-disk tribometer.The microstructure of CrCN films prepared at ion current density of 10 μA/cm2 was observed Cr2N and CrN peaks. On the other hand, XRD patterns of the films prepared above 30μA/cm2 suggested that CrN and Cr7C3 existed in the mixture phase in these films. The Knoop hardness and the wear resistance of CrCN films prepared above 30 μA/cm2 showed a high value and a low friction coefficient, respectively. It was considered that the formation of Cr-carbide in CrCN films contributed to the improvement of the mechanical properties.