In automatic cruising control according to the distance between the preceding and this vehicle (inter-vehicle distance), acceleration and deceleration force information is visually or acoustically provided to the driver. A value corresponding to an actual inter-vehicle distance and actual acceleration and deceleration of the vehicle is detected to control according to a target acceleration and deceleration value. The target acceleration and deceleration value is determined so as to equalize the value to a target value corresponding to a target inter-vehicle distance. The driver of the vehicle is informed that at least one of the target acceleration and deceleration value and the actual acceleration and deceleration of the vehicle reaches a predetermined threshold value. The level of acceleration and deceleration force in automatic cruising may be informed. Information may be provided to the driver when the acceleration and deceleration reaches the upper or lower limit or maximum value.