POWER SUPPLY SYSTEM

The power supply system includes: a first power circuit having a first battery, a second power circuit having a second battery, a voltage converter which converts voltages between both circuits, voltage sensors which acquire a first circuit voltage value V and second circuit voltage value V, a current sensor which acquires a passing current value Iact, and a passing power control unit which operates the voltage converter. The passing power control unit performs PWM control under a control duty ratio obtained by summing a correction duty ratio calculated based on the current deviation change rate and a base duty ratio, in a case of, after starting PWM control under the base duty ratio decided based on the voltage values V, V during activation of the voltage converter, the value of current deviation between a passing current value Iact and activation target value Itrg exceeding a permitted range.