Cubic boron nitride (cBN) films were deposited by ion-beam-assisted vapor deposition method. Effects of the ion current density, the baron deposition rate, the composition of the supplied gas into the ion source on the cBN formation range and deposition;rate at an ion energy of 0.5 keV were studied. cBN films were obtained at almost constant ratio of boron deposition rate to ion current density, depending on the composition of the supplied gas. The deposition rate of cBN films, whose maximum was 0.5 nm s(-1) increased almost linearly with increasing the boron deposition rate. The grain sizes of the obtained films were increased with increasing the cBN deposition rate. The diffraction patterns from cBN (111), (220), (311), and (222) were observed on the transmission electron diffraction.