To provide a gas vent system used for a vacuum chamber and capable of preventing the pollution due to micro-dust formed by the gas vent process in the vacuum chamber.

The gas vent system of the vacuum chamber 36 is provided at least with a gas supply end 22, a vibration proof gas transmitting pipe line 24 provided successively to the next of the gas supply end 22 and for preventing the propagation of the vibration of the gas supply end 22 to the vacuum chamber by transmitting a gas, a gas flow rate regulator 26 provided successively to the next of the vibration proof gas transmitting pipe line 24 and for controlling the flow rate of the gas, a 1st pipe line 28a provided successively to the next of the gas flow rate regulator 26 and containing a 1st needle valve, a 2nd pipe line 28b provided successively to the next of the gas flow rate regulator 26 in parallel to the 1st pipe line 28a and containing a 2nd needle valve and a serial control valve 28b2, a gas supply control valve 30 provided successively to the next of the 1st pipe line 28a and the 2nd pipe line 28b, and a filter 32 provided successively between the gas supply control valve 30 and the vacuum chamber 36.