POWER SUPPLY SYSTEM

In the power supply system, DC/DC converter may perform a first operation of converting a voltage of the output node into a charging voltage and supplying the charging voltage to the sub power supply, and a second operation of converting a voltage of the sub power supply into an output voltage and supplying the output voltage to the output node. The load is connected to the output node via a power supply line, and includes a voltage detection unit that detects a voltage output from the power supply line. Control unit (control unit and the control unit) is to conduct the first switch, by causing DC/DC converter to execute the first operation, to charge the sub power supply, after charging the sub power supply, switching the first switch to non-conductive, DC/DC converter to execute the second operation, detects an abnormality based on the voltage detected by the voltage detection unit.