A FOUP opening/closing device includes a housing containing a mounting table for mounting the FOUP thereon, an FOUP loading opening, and a delivery opening. The device further includes a rotator for rotating the mounting table, a door opening/closing unit to open or close the door of the FOUP and keep the door open, a mover for moving the FOUP and the door opening/closing unit in a reciprocating manner, to allow the FOUP and the door opening/closing unit to be connected to or separated from each other, and a controller to output control signals for moving the FOUP and the door opening/closing unit via operation of the mover to mount the door of the FOUP to the door opening/closing unit, separating the door from the FOUP, moving the FOUP and the door opening/closing unit away from each other, and rotating the mounting table to make the FOUP face the delivery opening.