A control device that controls an electric motor drive device is configured with a current control portion that determines a voltage command value, a voltage control portion that generates a switching control signal, and a current control period determining portion. The control device is also configured with a voltage control period determining portion that determines a voltage control period, and a control period setting portion. In the control device, the current control period determining portion determines, according to a target torque, the current control period as a value that increases continuously or stepwise as the target torque decreases. Furthermore, the voltage control period determining portion determines, according to a rotating speed, the voltage control period as a value that increases continuously or stepwise as the rotating speed decreases.