A power supply system includes a plurality of DC-DC converters and at least one operating unit. The DC-DC converters are connected in parallel to one another. The at least one operating unit operates the DC-DC converters such that power is supplied through the DC-DC converters to a predetermined power-supplied object. The at least one operating unit includes a voltage controller, a current limiter, and an increasing unit. The voltage controller operates the DC-DC converters such that output voltages thereof are controlled to be respective target voltage. The current limiter limits output currents of the DC-DC converters so that they are limited with respect to a respective specified value. The increasing unit increases a specified value for at least one DC-DC converter of the DC-DC converters, when all of the plurality of DC-DC converters are activated and output current of at least one other DC-DC converter of the DC-DC converters reaches a specified value for the at least one other DC-DC converter.