FIG. 8 illustrates a modified example of the normal screen to be displayed at the behavior display area 35a of the monitor device 24. In this modified example, a picture image 40 indicating the travelling own vehicle is added to be displayed at the behavior display area 35a. The picture image 40 is an image obtained by imitating a shape of the entire own vehicle viewing slightly obliquely from the above on a road and is previously prepared and stored in the display information storing unit 6.