Provided is an endoscope gas-supply system which enables to measure the intraluminal pressure of a human lumen unaffectedly by body motions, and to stably perform automatic gas supply into the lumen. In the endoscope gas-supply system, a gas-supply duct for automatic gas supply from a gas-supply apparatus into the lumen includes a buffer tank which has a predetermined volume. The intraluminal pressure of the lumen is indirectly obtained from a result of measurement of a pressure sensor in the gas-supply apparatus, and pressure control is performed such that the intraluminal pressure of the lumen becomes a set value. At this time, intraluminal pressure fluctuation due to volume variation of the lumen is absorbed at the buffer tank, so the pressure sensor can perform pressure measurement stably, and stabilization of automatic gas supply into the lumen can be achieved.
