PROBLEM TO BE SOLVED: To provide an endoscope gas-supply system which enables to measure intraluminal pressure unaffectedly by body motions, and to stably perform automatic gas supply into the lumen.SOLUTION: In the endoscope gas-supply system, a gas-supply duct for automatic gas supply from a gas-supply apparatus 102 into the lumen includes a buffer tank 106, where a duct resistance A on the upstream side (the side of the gas-supply apparatus 102) from the buffer tank 106 is larger than a duct resistance B on the downstream side from the buffer tank 106. The intraluminal pressure is indirectly obtained from a result of measurement of a pressure sensor 136 for measuring pressure inside the buffer tank 106, and pressure control is performed such that the intraluminal pressure becomes a set value. Consequently, stabilization of automatic gas supply into the lumen can be achieved while suppressing the influence of gas supply from the gas-supply apparatus 102.
