Disclosed herein are embodiments of controllers and methods of control to enable prevention of departure of vehicle even when the degree of the tendency of the vehicle to depart from the travel lane is low. One such controller comprises a lane departure tendency determining device configured to determine a departure tendency of the vehicle to depart from a travel lane, a yaw moment computing device configured to compute a reference yaw moment based on the departure tendency, a yaw moment correction device configured to compute a target yaw moment based on at least the reference yaw moment and a controller configured to apply the target yaw moment to the vehicle. When the reference yaw moment is lower than a prescribed threshold, the yaw moment correction device gradually increases the target yaw moment over time until the target yaw moment is greater than the prescribed threshold.