In the examples of FIGS. 7A and 7B, each of the symbol images 37, 37′ for the travel course is formed as an arrow mark consisting of an arrow-head portion and a stem portion. To cause the travel direction to be easy to be recognized at a glance, the stem portion is tapered from the own vehicle side to the front side and the arrow-head portion is tapered frontward as well in accordance therewith. In FIGS. 7A and 7B, since the travel course is straight, the symbol images 37, 37′ are straight arrow marks. Naturally, when the travel course is curved, the arrow mark is to be curved in accordance therewith.