An isolator system comprising: a box-shaped body case having, in an interior thereof, a work space for operation in a sterile environment and also having, in a front surface thereof, an insertion portion into which a worker's arm is inserted; and an air-conditioning portion configured to supply gas in the work space of the body case or to discharge gas in the work space, wherein: a bottom of the work space is configured with a work plate, a discharge path configured to discharge gas in the work space is formed below the work plate, the work plate is configured with first and second work plates (111a, 111b) obtained by dividing the work plate into right and left parts, characterized by a receiving portion located below the first work plate and, the receiving portion is arranged to extend towards the second work plate on a side edge of the first work plate, the side edge of the first work plate is in contact with the second work plate, and on the receiving portion, the side edge of the second work plate to be in contact with the first work plate is placed detachably, wherein when the second work plate is placed on the receiving portion of the first work plate, a top surface of the first work plate and a top surface of the second work plate are disposed in a same plane, and wherein on a lower surface of the second work plate, a reinforcing portion configured to prevent the second work plate from bending or vibrating is provided on the side edge of the second work plate which is in contact with the first work plate. a box-shaped body case having, in an interior thereof, a work space for operation in a sterile environment and also having, in a front surface thereof, an insertion portion into which a worker's arm is inserted; and an air-conditioning portion configured to supply gas in the work space of the body case or to discharge gas in the work space, wherein: a bottom of the work space is configured with a work plate, a discharge path configured to discharge gas in the work space is formed below the work plate, the work plate is configured with first and second work plates (111a, 111b) obtained by dividing the work plate into right and left parts, characterized by a receiving portion located below the first work plate and, the receiving portion is arranged to extend towards the second work plate on a side edge of the first work plate, the side edge of the first work plate is in contact with the second work plate, and on the receiving portion, the side edge of the second work plate to be in contact with the first work plate is placed detachably, wherein when the second work plate is placed on the receiving portion of the first work plate, a top surface of the first work plate and a top surface of the second work plate are disposed in a same plane, and wherein on a lower surface of the second work plate, a reinforcing portion configured to prevent the second work plate from bending or vibrating is provided on the side edge of the second work plate which is in contact with the first work plate. a bottom of the work space is configured with a work plate, a discharge path configured to discharge gas in the work space is formed below the work plate, the work plate is configured with first and second work plates (111a, 111b) obtained by dividing the work plate into right and left parts, characterized by a receiving portion located below the first work plate and, the receiving portion is arranged to extend towards the second work plate on a side edge of the first work plate, the side edge of the first work plate is in contact with the second work plate, and on the receiving portion, the side edge of the second work plate to be in contact with the first work plate is placed detachably, wherein when the second work plate is placed on the receiving portion of the first work plate, a top surface of the first work plate and a top surface of the second work plate are disposed in a same plane, and wherein on a lower surface of the second work plate, a reinforcing portion configured to prevent the second work plate from bending or vibrating is provided on the side edge of the second work plate which is in contact with the first work plate.