PURPOSE: To detect the connection between a main body and a peripheral equipment by detecting the connection between the video equipment main body and the video peripheral equipment pure electrically so as to send/receive a video signal from the main body to the peripheral equipment without increasing the size of a connector without provision of a push switch or a special pin.

CONSTITUTION: A video signal is amplified by an amplifier circuit AT at the video equipment main body side, and fed to a connector TT at the main body side through a DC block capacitor CD and a termination resistor RT. Then resistors RD and RE (=2×RD) form reference voltage generating resistors and a reference voltage is generated by dividing the voltage across the resistors. Then the reference voltage is compared with a voltage at a connecting point between the termination resistor RT and a connector TT at a comparator 1 to detect the connection state between the connectors TT and TR. That is, when the connectors TT and TR are connected, the detection output of the comparator 1 goes to a high level.