The invention provides a charge/discharge system equipped with a first and a second charging device for supplying power to a motor generator, and charging using the power generated by the motor generator, a power conversion device, and a control device, wherein when power charged in the first charging device is supplied to the motor generator, and the charging capacity of the first charging device drops to or below a second prescribed value, the control device controls the power conversion device so as to charge the first charging device using the power stored in the second charging device, and when the charging capacity of the first charging device drops to or below a first prescribed value, reduces the drive power of the motor generator according to the charging capacity.