In a state where an incubator 3 is connected to an isolator 2 through a chamber 4 and opening/closing doors 11B and 12 are closed, a decontaminating gas G is supplied to the chamber 4 through gas supply passages 16 and 26, and an inside thereof is decontaminated.Subsequently, an air is supplied into the chamber 4 through the gas supply passages 16 and 26 and initial aeration is carried out by discharging a gas in the chamber 4 through a gas discharge passage 27.Subsequently, after the opening/closing door 11B is opened, when both blowers B1 and B4 are stopped, the gas at a positive pressure in the isolator 2 is introduced into the chamber 4. Thus, the gas containing the decontaminating gas G in the chamber 4 is rapidly discharged to an outside through the gas supply passages 26 and 16 and the gas discharge passage 27, and aeration in the chamber 4 is completed.Time required for the aeration of the chamber 4 can be drastically reduced as compared with before.
