FIGS. 13A to 13D illustrate, in the order of time passage, a transition of that the virtual image 46′ of the own vehicle displayed at the monitor device 24 performs lane change. First, the virtual image 46′ starts, on the taken scenery 39, as a virtual image 461′ in FIG. 13A illustrating a virtual vehicle having appearance and size as if the virtual vehicle is travelling just in front of the own vehicle. The virtual vehicle moves from the position just in front of the own vehicle to the cruising lane 45′ to be apart therefrom while changing orientation of the vehicle body as being similar to the actual vehicle along the travel course of the symbol image 44′ as illustrated by the virtual images 462′, 463′ in FIGS. 13B and 13C. Then, as illustrated in FIG. 13D, the virtual vehicle completes movement to be the virtual image 464′ that is oriented to straightly travel on the cruising lane 45′.