Gas supplying apparatus, cylinder cabinet provided with the same, valve box, and substrate process apparatus

A gas supplying apparatus that supplies a gas to a chamber where a process is carried out with respect to a substrate at a process pressure less than an atmospheric pressure, the gas supplying apparatus comprising:

• a pressure controller that reduces a primary pressure thereby providing a secondary pressure greater than the process pressure and less than the atmospheric pressure in a secondary pipe;
• a pressure sensor that measures a pressure in the secondary pipe;
• a first open/close valve provided in the secondary pipe;
• an open/close valve controller that opens or closes the first open/close valve;
• a pressure comparator that compares the pressure measured by the pressure sensor in the secondary pipe with a first set pressure that is greater than the process pressure by a predetermined pressure;
• and
• a controller that outputs a signal to the open/close valve controller thereby closing the first open/close valve, when the pressure comparator determines that the pressure in the secondary pipe is less than the first set pressure.