PURPOSE: To prevent deterioration in the physical characteristic of a deposited film owing to overheating of a gaseous raw material in the stage of decomposing the gaseous raw material by electric discharge and forming the deposited film on a base body by heating preliminarily the gaseous raw material to a prescribed temp. and supplying said material.

CONSTITUTION: A cylindrical substrate 2 is set in a vacuum chamber 1 and the inside of the vessel is evacuated to a vacuum by an evacuating system 7. A pipe 6 for supplying a gaseous raw material is heated by a heater 8 and when a prescribed temp. is attained, the gaseous raw material heated to the prescribed temp. is supplied through the pipe 6 into the chamber 1 while a base body 2 is rotated by a rotating mechanism 9. The gaseous raw material is released from the many holes provided to the release pipe 11 in the chamber 1 toward the body 2. The high-frequency voltage from a high-frequency power source 5 is at the same time impressed between the vacuum vessel 1 as a cathode and the base body 2 of the grounded anode to generate glow discharge between both electrodes thereby decomposing the gaseous raw material and forming a deposited film on the base body 2. Since there is no heater in the chamber 1, the overheating of the gaseous raw material as a result of direct contact with the heater is obviated and the deposited film having excellent electrical properties and optical properties is obtd.