A power supply controller is connected between a power source and a power-supply path, and includes a switch circuit, a power-supply path protection circuit, and a sleep mode setting circuit. The switch circuit is configured to permit and inhibit power supply from the power source to the load. The protection circuit controls switching operation of the switch circuit according to a power-supply command signal commanding start or stop of the power supply to the load, calculates a temperature of the power-supply path regardless of whether power is supplied to the load, do not calculate the temperature of the power-supply path in a sleep mode, and inhibits power supply to the switch circuit according to the calculated temperature reaching an upper limit. The sleep mode setting circuit sets the power supply controller to the sleep mode according to the of the power-supply path satisfying a temperature condition.