Abstract: A chemical vapor deposition apparatus comprising: a reaction chamber for defining an enclosed space; a pedestal arranged within the reaction chamber on which a substrate is settled; heater means arranged within the pedestal for heating the substrate; a gas inlet for introducing gas into the reaction chamber; a gas outlet for exhausting gas from the reaction chamber; and a gas injector extended from the end of the gas inlet, wherein the gas injector has a hollow side wall so that a heat exchanging medium can flow through the side wall, and inlet and outlet ports arranged in the outside of the sidewall, each of the inlet and outlet ports communicating with the inside of the side wall. Here, the outlet port is arranged higher than the inlet port.