1. A navigation control system for an automotive vehicle running on a road, comprising: deviation detecting means for detecting that the vehicle has deviated or is going to deviate from a lane of the road; deviation suppressing means for suppressing the vehicle from deviating from the lane; detection means for detecting a predetermined condition affecting deviation of the vehicle from the lane; and control means for computing a control amount for suppressing the deviation of the vehicle based on a result of detection by said deviation detecting means, for determining a urgency rating for said deviation suppressing based on said detected predetermined condition and said control amount, and for controlling said deviation suppressing means on the basis of a result of the computing the control amount, said deviation suppressing means being controlled by altering a time for operating said deviation suppressing means in accordance with said urgency rating for said deviation suppressing.