An isolator system includes an isolator, passbox, clean booth, and decontamination gas supply. The isolator includes a sterile operation area and a wearing entity for an operator. The passbox enables introducing an object into the sterile operation area. The clean booth, encloses an insertion port of the wearing entity and an inlet port for introducing the object into the passbox. A clean gas supply supplies clean gas to the sterile operation area and to the clean booth. The decontamination gas supply supplies decontamination gas into the sterile operation area and the clean booth. After an interior of the sterile operation area and the clean booth are decontaminated, pressures of the sterile operation area and the clean booth are maintained at least equal to a building pressure and the pressure of the clean booth is maintained lower than a pressure of the sterile operation area.