For example, as illustrated in FIG. 7B, the second display device 4 displays, in real time, a moving image of scenery 39 in front of the own vehicle taken by the front cameras 16, 16 at the behavior display area 35a of the monitor device 24. A symbol image 37′ of the travel course of the own vehicle is displayed as being superimposed to an overtaking lane 38′ of the taken scenery 39. Since a lane location in front of the travelling own vehicle can be recognized at high accuracy with the front cameras 16, 16, it is relatively easy to perform accurate positioning of the symbol image 37′ with respect to the taken scenery 39 projected to the behavior display area 35a.