An interface device is provided which is capable of eliminating the need for mounting an external resistor and of reducing manufacturing costs for the interface device. An internal resistor and a PMOS(p-channel Metal Oxide semiconductor) switch are serially connected between a non-inverted input terminal of an LVDS (Low Voltage Differential Signaling) receiver of a D channel out of LVDS signal channels. An NMOS (n-channel MOS) switch and an internal resistor are serially connected between an inverted input terminal of the LVDS receiver and a ground (GND). To a gate input terminal of the PMOSswitch is connected an terminal for an idle terminal setting input terminal while an inverter is connected to an gate input terminal of the NMOS switch.