To provide a constitution capable of increasing an oxygen concentration in the air in such an object space that a composition is adjusted by an air composition adjustment device, higher than an oxygen concentration in the atmosphere.SOLUTION: An air composition adjustment device 30 is provided with an oxygen separation part 41 for separating oxygen from the outside air supplied into an object space 5, a gas supply route 135 including a high concentration gas supply route 136 for oxygen for allowing communication from the oxygen separation part 41 to the object space 5, and a controller 110 for performing an oxygen concentration increasing operation for supplying high oxygen concentration gas having a higher oxygen concentration than the state before a treatment by the oxygen separation part 41, into the object space 5 through the high concentration gas supply route 136 for oxygen.SELECTED DRAWING: Figure 3【課題】空気組成調節装置で組成が調整される対象空間の空気の酸素濃度を大気中の酸素濃度より高濃度にする構成を提供する。【解決手段】対象空間５へ供給される外気から酸素を分離する酸素分離部４１と、酸素分離部４１から対象空間５へ連通する酸素用高濃度ガス供給経路１３６を含むガス供給経路１３５と、酸素分離部４１での処理前よりも酸素濃度が高い高酸素濃度ガスを対象空間５へ酸素用高濃度ガス供給経路１３６を通じて供給する酸素濃度上昇動作を行う制御器１１０とを空気組成調節装置３０に設ける。【選択図】図３
