To provide a switching circuit which enables coping with the side of an externally connected apparatus, when there is slight abnormality.

This switching circuit has a MOS transistor Q1; a circuit (a resistor R2 and a resistor R3) for detecting the input voltage of the MOS transistor Q1; a circuit (a resistor R4 and a resistor R5 ) for detecting the output of the MOS transistor Q1; a detection circuit ( a resistor R1 and an operational amplifier 4) for a current flowing in the MOS transistor Q1; a detection circuit ( a temperature sensor 5) for the ambient temperature of the MOS transistor Q1; and a logic circuit 6 which controls the ON/OFF of the MOS transistor Q1, according to the detection results of each detection circuit, and also outputs the detection results of each detection circuit to outside via a data output terminal 7 as a digital signal.