A DC power supply system includes: a DC bus serving as a bus bar for DC power supply; a natural energy power generator 30 that supplies generated power to the DC bus; a plurality of storage batteries that store the generated power from the natural energy power generator; a plurality of bidirectional DC-DC converters that connect the plurality of corresponding storage batteries to the DC bus; a power management apparatus that manages operations of the plurality of bidirectional DC-DC converters; and a target voltage corrector that calculates a correction value of a target value for the output voltage by using an average value of a plurality of actual measurement values of each output voltage of the bidirectional DC-DC converters. The power management apparatus individually controls the each output voltage of the bidirectional DC-DC converters by using each target value of the output voltages corrected based on the correction value.