PURPOSE: To eliminate an adverse influence caused by reaction product dust, and secure worker's safety, by installing a gas curtain forming means which spouts a gas curtain outside a gas recovering cover.

CONSTITUTION: A gas feeding head 2 which spouts reaction gas, and a gas recovering cover 1 arranged around the head 2 are installed. A gas curtain forming means 4 which spouts a gas curtain is installed on the outer periphery of the gas recovering cover 1. Inert gas, like N2, supplied from a curtain gas feeding port 5 is made to flow through a pipe inside the gas curtain forming means 4. Hence the inside and the outside of a gas feeding equipment 18 are isolated, and the leak of reaction gas and the permeation of air can be prevented. Thereby a worker can be protected from the danger to be exposed to poisonous gas, and a wafer can be prevented from being contaminated by dust.