Further, an X mark being an attention-calling mark 62, 62′ is displayed at each of the first and second display devices 3, 4 for causing the occupant to recognize the obstacle on the scheduled travel course. The attention-calling mark 62 is displayed at the front windshield 15 at a position on the cruising lane 51 near a building 63 to indicate that a large-sized vehicle 64 being the obstacle is parking/stopping behind the building 63. Similarly, the attention-calling mark 62′ is displayed at the monitor device 24 at a position on the cruising lane 51′ near a building 63′. It is preferable that the attention-calling mark 62, 62′ is displayed in a striking color such as red and orange, and further, is displayed as being blinked.