In lane keep control apparatus and method for an automotive vehicle, a behavior of the vehicle is controlled in such a manner that a yaw moment is developed in a direction to avoid a deviation of the vehicle from the traffic lane in accordance with the traveling state of the vehicle when determining that the vehicle has a tendency of the deviation of the vehicle from the traffic lane and lane markers are detected, each lane marker representing one side of the traffic lane, and the behavior of the vehicle is controlled on the basis of the detected lane marker at one side of the traffic lane when a detection state of the lane markers is transferred from a state in which both of the lane markers at both sides of the traffic lane are detected to a state in which the lane marker only at one side of the traffic lane is detected.