An image processing unit identifies the shape of an obstacle that is identified from an area that appears in a peripheral image based on an image captured by a camera. The shape of the obstacle includes at least a tilt of a section of the obstacle in a road-surface direction. The section of the obstacle faces a vehicle. The image processing unit generates a superimposed image in which a mark image that is generated as a pattern that indicates the identified obstacle is superimposed onto a position that corresponds to the obstacle in the peripheral image. At this time, the image processing unit variably changes properties of the mark image based on the tilt of the obstacle identified by an obstacle identifying unit. The image processing unit then displays the generated superimposed image on display apparatus.