Cubic boron nitride (c-BN) films have been developed by ionized deposition from evaporated boron and nitrogen gas at a pressure of 10~(-1) Pa. The film structures were examined by transmission electron microscopy and electron diffraction. It was found that the structure of BN films could be divided into the following categories amorphous, hexagonal, cubic, and their mixtures. The average grain size of c-BN films was estimated to be less than few thousand angstroms. These stuctures and grain sizes depended mainly on the deposition conditions such as substrate potential, temperature, and ion current density.