The invention provides a semiconductor processing system including a semiconductor processing apparatus and a gas supply apparatus for supplying a process gas into the semiconductor processing apparatus, which includes a control section configured to control an operation of a pressure adjusting mechanism for adjusting the pressure inside a vaporizing chamber. The control section is preset to cause the pressure inside the vaporizing chamber to fall within a predetermined pressure range with reference to a pressure detection value obtained by a pressure detector. The predetermined pressure range is defined by an upper limit lower than a first limit value, at which vaporization of the liquid material starts being inhibited due to an increase in the pressure, and a lower limit higher than a second limit value, at which vaporization of the liquid material starts being unstable and the pressure inside the vaporizing chamber starts pulsating movement due to a decrease in the pressure.