PROBLEM TO BE SOLVED: To provide an endoscope system which enables switching operation with the same operational feeling to achieve an air supply state regardless of whether the switching button selectively mounted on a cylinder of the operation unit is an air/water supply button or a gas/water supply button.SOLUTION: An endoscope system 90 comprises: an endoscope 10 having a nozzle 15a provided at a distal end part 15 of an insertion part 11 an air/water supply device 91 for supplying fluid and a gas cylinder 92. The endoscope system 90 further includes: a cylinder 1 which is provided in an operation unit 12, and to which is coupled the other end part of a nozzle side air supply conduit 9Ab one end part of which is coupled to the nozzle 15a a supply-source side air supply conduit 9Aa for supplying a fluid or the like from the gas cylinder 92 and an air/water button 30 and a gas/water supply button 40 which are selectively mounted on the cylinder 1. The energizing force of coil springs 75a, 75b provided for the gas/water supply button 40 is smaller than the value obtained by multiplying the area of the open end 34e of an opening hole 34h provided for a first piston 33 by the pressure of the fluid supplied from the air/water supply device 91 and blowing out from the opening hole 34h.SELECTED DRAWING: Figure 3COPYRIGHT: (C)2016,JPO&INPIT【課題】操作部のシリンダに選択的に装着される切換ボタンが送気送水ボタン又は送ガス送水ボタンに関わらず同じ操作感で切換操作を行って送気状態を得られる内視鏡システムを提供する。【解決手段】内視鏡システム90は、挿入部11の先端部15にノズル15aを設けた内視鏡10と、流体を供給する送気送水装置91、ガスボンベ92とを備え、操作部12に設けられノズル15aに一端部が連結されたノズル側送気管路9Abの他端部が連結されるシリンダ1と、ガスボンベ92からの流体等を供給する供給源側送気管路9Aaと、シリンダ1に選択的に装着される送気送水ボタン30及び送ガス送水ボタン40と、を具備し、送ガス送水ボタン40が有するコイルスプリング75a、75bの付勢力は、第1のピストン33に設けられた開放孔34hの開口端34eの面積と送気送水装置91から供給されて開放孔34hから噴出する流体の圧力とを乗じた値よりも小さい。【選択図】図3
