YNx films were prepared by the rf reactive ion plating method. The composition of the films were altered by changing the rf power and Ar/$N_2$ ratio. The films exhibited metallic and semiconductive electrical conductive behavior depending on the film composition. The hardness of the films reached HD900, which meant that the films were harder than sodalime glass. The XPS result revealed the chemical shifts of 2.6eV for the Y 3d peak and -1.9eV for the N ls peak by the formation of Y-N bonds.