To provide an oxygen concentrator which can stably supply concentrated oxygen gas of low concentration of 40% or the like, and supply concentrated oxygen gas optimum for medical treatment for an infant patient such as a premature baby.SOLUTION: An oxygen concentrator includes a control means which includes: an oxygen supply line including an oxygen storage means of accumulating generated concentrated oxygen gas, a pressure regulating valve, a first oxygen flow amount control valve for supplying concentrated oxygen gas after pressure regulation to a user, an oxygen concentration measurement means of measuring the oxygen concentration of the concentrated oxygen gas, and a flow amount measurement means of measuring an oxygen flow amount and an oxygen exhaust line including a second oxygen flow amount control valve for discharging concentrated oxygen gas after pressure regulation to the outside of a system, and controls an opening of the first oxygen flow amount control valve on the basis of an oxygen supply flow amount set value and a measured value of the flow amount measurement means, and controls an opening of the second oxygen flow amount control valve so as to bring to a previously set oxygen concentration.SELECTED DRAWING: Figure 3【課題】 40%などの低濃度酸素濃縮ガスを安定的に供給することができ、未熟児などの乳幼児患者の治療に最適な酸素濃縮ガスを供給する酸素濃縮装置を提供する。【解決手段】 生成した酸素濃縮ガスを貯留する酸素貯蔵手段、調圧弁、調圧後の酸素濃縮ガスを使用者に供給する第1酸素流量制御弁、該酸素濃縮ガスの酸素濃度を測定する酸素濃度測定手段、酸素流量を測定する流量測定手段を備えた酸素供給ラインと、調圧後の酸素濃縮ガスを系外に放出する第2酸素流量制御弁を備えた酸素排気ラインを備え、酸素供給流量設定値および該流量測定手段の測定値に基づいて第1酸素流量制御弁の開度を制御すると共に、予め設定された酸素濃度となるように、第2酸素流量制御弁の開度を制御する制御手段を備えたことを特徴とする酸素濃縮装置。【選択図】 図3
