Abstract: A source-gas supply apparatus for supplying a source gas into a CVD reactor includes: a reservoir for storing a liquid material; a gas flow path connected the reservoir and the CVD reactor; a sonic nozzle disposed in the gas flow path, through which the source gas is introduced into the CVD reactor; a pressure sensor disposed in the gas flow path upstream of the sonic nozzle; a flow control valve disposed in the gas flow path upstream of the pressure sensor; and a flow control circuit which receives a signal from the pressure sensor and outputs a signal to the flow control valve to adjust opening of the flow control valve as a function of the signal from the pressure sensor.