To minimize the cost and loss rate of energy artificial room ventilation system, the O2 separator was suggested for the flow of the excessive ventilation amount between indoor and outdoor because the pure O2 separated and concentrated by the O2 separator can be supplied with the ventilation amount minimized. How the O2 separator applies to ventilation and its operation characteristics were investigated by controlling under various conditions as well as the operation conditions optimized required for indoor air quality such as the concentration of CO2 and O2. Consequently, it was known that the O2 concentration was increased; however, the increase of the CO2 concentration was suppressed by the sufficient supply of O2 concentrated from the storage tank into the room despite the two persons’ breathing in the room having an inner volume of about 56m3. Consequently, it was concluded that the supply system of the concentrated O2 which was stored into the tank after the production with the O2 separator can be applied to the room ventilation system for the improvement of the indoor air quality.