POWER SUPPLY SYSTEM

A power supply system includes: a capacitive first battery; an output-type second battery having a smaller heat capacity than the first battery; a voltage converter that converts a voltage between first and second power circuits; a power converter that converts power between the first power circuit and a drive motor; and a power controller that operates the voltage converter and the power converter. The power controller is configured to: after a start of operation, execute a power pass control under which power is transferred between the first and second batteries, until a total output upper limit Ptot_max of all the batteries exceeds a travelable threshold value Pready1; and subsequent to the power pass control, execute a second priority control under which the second battery is discharged in preference to the first battery, until a first output upper limit P1_max of the first battery exceeds a margin traveling threshold value Pready2.