PURPOSE: To increase the rate of formation of a hard carbon film by evaporating carbon atoms by irradiation with electron beams, passing the carbon atoms through a high frequency coil together with hydrogen molecules to cause ionization and carrying out vacuum deposition on a substrate.

CONSTITUTION: When a hard carbon film is formed with an ion plating device, the vacuum chamber 11 is evacuated and H2 is introduced to keep the chamber 11 at a prescribed degree of vacuum. Graphite 4 in a crucible 5 is irradiated with electron beams 8 to evaporate C. At the same time, high frequency power is impressed on a high frequency coil 2 to generate plasma of C and H in the electric discharge region and a hard carbon film is formed on a substrate 12 to be treated. The rate of growth of the transparent hard carbon film having superior insulation resistance can be made higher than that be the conventional method by a figure or more.