PURPOSE: To execute stable deposition by preventing the destruction of a film by collision of ions.

CONSTITUTION: This device has a housing 11 for introducing a gaseous raw material G, such as silicon fluoride, in one direction by reduced pressure air flow, a gas cracking means 12 which is provided upstream of this housing 11 and converts the gaseous raw material G to plasma by a high-frequency discharge, etc., a substrate 13 which is provided downstream of the housing 11 apart a prescribed distance from this gas cracking means 12 and a grid 14 which is grounded and is provided between the substrate 13 and the gas cracking means 12 and is a trapping means for capturing only the ions among the particles cracked by the conversion to the plasma.