An endoscope air-supply system comprising: a gas supply device which supplies predetermined gas to a lumen of a subject through an air-supply duct； a pressure measurement device which measures pressure in the lumen and which is connected through a duct for pressure measurement communicating with the lumen； a flushing device which supplies gas for flushing to the duct for pressure measurement； and an instruction device which instructs the pressure measurement device to perform pressure measurement and which instructs the flushing device to supply the gas for flushing in synchronism with the pressure measurement by the pressure measurement device.
