A scanner sharing device includes a scanner device connection terminal for a scanner device to be connected thereto, a plurality of computer connection terminals for a plurality of computers to be connected thereto, a connection switching unit selectively connecting one of the plurality of computer connection terminals with the scanner device connection terminal, and a switch control unit controlling the operations of the connection switching unit. When the scanner sharing device is in an automatic switching mode, the switch control unit maintains the connection between the computer connection terminal associated with that one computer and the scanner device connection terminal until the switch control unit receives a processing completion signal.