In another embodiment, the display device uses a monitor device mounted on a dashboard of the own vehicle for prior notice displaying with picture images. Here, modifications and image processing that are difficult to be performed on actual scenery serving as a background image, and a variety of image displaying other than the abovementioned picture images can be displayed as being added to roads of taken images and virtual images displayed on the monitor device. Accordingly, it is possible to provide more information to an occupant in relation to the unscheduled travel behavior of the own vehicle to be subsequently performed.