A target steering angle calculator calculates, based on a target curvature, a target steering angle representing a steering angle of the vehicle at a target position. A current steering-angle obtainer obtains a current steering angle representing a steering angle of the vehicle at a current position. A steering controller controls the steering of the vehicle to cause the current steering angle to follow the target steering angle. A distance estimator estimates, based on at least one of the environmental information around the vehicle and control information about the vehicle, a visible distance representing a distance visibly recognizable by the driver of the vehicle to a front of the vehicle. The target curvature obtainer uses the visible distance as the target distance to obtain the target curvature at the predetermined target position that has the visible distance away from the current position along the road in the travelling direction.