To provide a gas measuring device capable of confirming whether or not gas exchange in the blood by an oxygenator is performed normally and an extracorporeal circulation system equipped with the gas measuring device.SOLUTION: The circulation circuit 2, the artificial lung 5 installed in the path of the circulation circuit 2, the centrifugal pump 4 for executing the extracorporeal circulation of the blood of the subject by the circulation circuit 2, the centrifugal pump 4 of the artificial lung 5 A connecting part 61 connected to the gas discharging part 54, and a connecting part 61 connected to the gas discharging part 54, a CO 2 measuring section for measuring the concentration of carbon dioxide in the steady flow exhaust gas obtained through the connecting part 61,2And a gas measuring device 6 having a sensor 62.BACKGROUND OF THE INVENTION【課題】人工肺による血液中のガス交換が正常に行われているか否かを確認することが可能なガス測定装置をおよび当該ガス測定装置を備える体外循環システムを提供する。【解決手段】循環回路2と、循環回路2の経路中に設置される人工肺5と、循環回路2による被検者の血液の体外循環を実行するための遠心ポンプ4と、人工肺5のガス排出部54に接続される接続部61、および接続部61を介して取得された定常流の排出ガスの二酸化炭素濃度等を測定するCO2センサ62を有するガス測定装置6と、を備える。【選択図】図1
