In an electric force transmission device employing two motor generators and a differential device having at least three rotating members and having two degrees of freedom, the first rotating member is coupled to the first motor generator, the second rotating member is coupled to the second motor generator, and the third rotating member is coupled to an output shaft and laid out to be located between the first and the second rotating members on an aligmnent chart. Also, a controller is configured to control the motor generators such that, when the output shaft is driven from its stopped state, before the driving is started, the first and second motor generators are rotated oppositely to each other, while keeping a rotational speed of the output shaft at the stopped state.