Properties of TiN films prepared by 8-38 keV N2 + ion implantations on Ti-coated (90-650 Å) fused SiO2 have been studied for heat mirror coatings. TiN films prepared by annealing Ti film in a nitrogen atmosphere and by sputtering were used as reference samples. The thicknesses and nitrogen contents of the films were measured with the nuclear resonance broadening method and Rutherford backscattering spectrometry. The infrared reflectances of the TiN films prepared by nitrogen implantation were somewhat lower than that of the reference films. The implanted TiN films had as good visible light transmittances as the films prepared by annealing but better than the sputtered films. The advantages of the nitrogen implantation in the preparation of TiN films are excellent adhesion and low preparation temperature.