A control apparatus calculates a total loss change amount that is a power loss change amount of a motor control system including respective power loss change amounts of a converter, an inverter, and a motor of the motor control system. Based on the total loss change amount, during a correction-allowed period that is a period during which square wave control is performed, the control apparatus performs correction to decrease a current output voltage command value of the converter when the current output voltage command value is determined to be greater than the output voltage of the converter at which actual total power loss change amount becomes minimum. When the current output voltage command value is determined to be less than the output voltage of the converter at which actual total power loss change amount becomes minimum, the control apparatus performs correction to increase the current output voltage command value.