PURPOSE: To stably form heat absorption material film with its excellent characteristics by properly lowering the performance to improve the degree of vacuum and maintaining it well after the film reaches the specified degree of vacuum during its deposition.

CONSTITUTION: While both the variable conductance and vacuum valves 12 and 13 are closing in the first place, the vacuum valve 9 opens and reaches the desired degree of vacuum by using the vacuum pump 10. Then, the vacuum valve 9 closes, current is applied to the evaporation source 7, and deposited material is evaporated. The deposition time vacuum valve 13 of the exhaust system into which the variable conductance valve 12 is inserted during deposition. By properly selecting the particle flow conductance of the variable conductance valve 12, the volume of gas produced during deposition is adjusted to be equal to that which is discharged by the piping system inclusing the deposition time vacuum valve 13 and the variable conductance valve 12.