Provided is a control device that stops the power supply when the first FET is short-circuited. In the control device, a boost circuit increases the voltage of one end of a resistor on the boost circuit side to a predetermined voltage that is higher than the source voltage of the first FET. An AND circuit instructs the discharge circuit to decrease the voltage at the other end of the resistor when the voltage at the other end of the resistor is less than a threshold voltage if the AND circuit instructs the boost circuit to increase the voltage at the one end of the resistor on the boost circuit side. The threshold voltage exceeds the voltage at the one end of the resistor if the voltage at the one end of the resistor on the boost circuit is the predetermined voltage and if the first FET is short-circuited.