An energy management system that includes a power generation apparatus that outputs generated electric power to a HVDC bus, a bidirectional DC-DC converter to which a DC voltage is input from the HVDC bus or outputting a DC voltage to the HVDC bus, and an inverter that converts a DC voltage inputted from the HVDC bus to an AC voltage. A calibration value is set to the highest voltage among voltages of the HVDC bus each detected by the power generation apparatus, the bidirectional DC-DC converter, and the inverter, other detection voltages are calibrated with the calibration value. Then, each of the power generation apparatus, the bidirectional DC-DC converter, and the inverter carry out switching control such that the detection voltage after the calibration match with a target value.