An electromotive drive system including a small motor and a small-capacity battery more effectively improves the fuel economy of an engine-driven vehicle. An electromotive drive system includes: a motor for driving a vehicle; a battery storing electrical energy to rotate the motor; an inverter; a converting mechanism transmitting rotation of the motor to a drive shaft at a predetermined conversion ratio independently of a conversion ratio at which an engine is driven; and a control unit controlling an operation of the inverter. The control unit is configured so that upper vehicle speed limits, to which the motor is allowed to operate, can be set separately during powering and during regeneration, respectively.