By applying an observing-point conversion and s synthesis to images captured by respective cameras capturing the surroundings of a vehicle and by placing a figure representing the vehicle on the synthesized image, an overhead-image generating unit generates an image to be obtained when captured at an observing point above the vehicle, a figure representing the vehicle, and an overhead image showing the surroundings of the vehicle in an overhead viewing manner, and displays the overhead image on a display device via a display processing unit. When an obstacle is detected by obstacle sensors, the caution-image generating unit extracts an image of those stored in an image memory, in an area including a part of the vehicle and the obstacle, generate a caution image, and displays the caution image at a position on the overhead image via the display processing unit corresponding to the position of the obstacle.