Comprising a pump for supplying or discharging gas to or from a balloon for fixing attached to a peripheral part of a tip part of an inserting unit of an endoscope and a control unit for controlling a pressure inside the balloon by operating the pump based on the measured result by measuring a pressure of gas inside the balloon wherein the control unit has an amount of flow detecting section for detecting the amount of flow of gas sent or drawn to or from the balloon, and controls the amount of flow of gas sent or drawn to or from the balloon by operating the pump based on the detected result by the amount of flow detecting unit.
