A controller for motor/generators is proposed which allows reductions in ripple current generated by an inverter driving a power-generating motor/generator and a vehicle-driving motor/generator. The control device for motor/generators has a first inverter which supplies a control current to a first motor/generator used mainly as an electrical motor, a second inverter which supplies a control current to a second motor/generator used mainly as a generator, a first PWM signal generating circuit which drives the switching elements of the first inverter based on a first carrier signal, a second PWM signal generating circuit which drives the switching elements of the second inverter based on a second carrier signal which has the same period of the first carrier signal. The first inverter and the second inverter are controlled so that the operation of the first inverter is synchronized with the operation of the second inverter and the current of the first inverter which flows in the DC bus line is generated in opposite direction to the current of the second inverter which flows in the DC bus line.