An isolator system comprising: a box-shaped body case including a work area, provided in an interior of the body case, in which work is conducted in a sterile environment, and an insertion portion, provided in a front surface of the body case, into which a worker's arm is inserted; a sterilizing unit configured to supply a sterilizing substance into the work area; an air conditioning unit (150,180) configured to supply and/or discharge gas with respect to the work area; a display unit with which a worker inputs a signal; a control unit configured to be coupled to the sterilizing unit, the air conditioning unit, and the display unit; and a storage unit configured to store a signal from the control unit, the control unit being configured to, after startup, confirm whether a concentration of a sterilizing substance in the work area is equal to or less than a predetermined concentration, or not, and when the concentration of the sterilizing substance in the work area exceeds the predetermined concentration, store in the storage unit a high concentration flag (concentration Hi flag) indicative that the concentration of the sterilizing substance in the work area is high, and thereafter, check an operation of the air conditioning unit (150,180), and if there is no problem with the operation of the air conditioning unit (150,160), confirm whether the high concentration flag (concentration Hi flag) is stored in the storage unit, and when the high concentration flag (concentration Hi flag) is stored, operate the air conditioning unit (150,180) for a predetermined time period, to lower the concentration of the sterilizing substance in the work area, and when the high concentration flag (concentration Hi flag) is not stored, aeration is not performed. a box-shaped body case including a work area, provided in an interior of the body case, in which work is conducted in a sterile environment, and an insertion portion, provided in a front surface of the body case, into which a worker's arm is inserted; a sterilizing unit configured to supply a sterilizing substance into the work area; an air conditioning unit (150,180) configured to supply and/or discharge gas with respect to the work area; a display unit with which a worker inputs a signal; a control unit configured to be coupled to the sterilizing unit, the air conditioning unit, and the display unit; and a storage unit configured to store a signal from the control unit, the control unit being configured to, after startup, confirm whether a concentration of a sterilizing substance in the work area is equal to or less than a predetermined concentration, or not, and when the concentration of the sterilizing substance in the work area exceeds the predetermined concentration, store in the storage unit a high concentration flag (concentration Hi flag) indicative that the concentration of the sterilizing substance in the work area is high, and thereafter, check an operation of the air conditioning unit (150,180), and if there is no problem with the operation of the air conditioning unit (150,160), confirm whether the high concentration flag (concentration Hi flag) is stored in the storage unit, and when the high concentration flag (concentration Hi flag) is stored, operate the air conditioning unit (150,180) for a predetermined time period, to lower the concentration of the sterilizing substance in the work area, and when the high concentration flag (concentration Hi flag) is not stored, aeration is not performed.