To facilitate discrimination of a curb, a gutter or the like by using an infrared illuminating device and an infrared-sensitive image pickup device mounted on an exterior mirror of a vehicle when the vehicle is pulled over to a shoulder at night. Two illuminating devices having optical axes oriented downward are mounted on a housing of a side mirror at a distance from each other in the lateral direction of a vehicle. The illuminating devices alternately emit infrared light downwardly. An image pickup device sensitive to infrared light having an optical axis oriented downward is mounted on the housing at a middle position between the left and right illuminating devices. An image taken by the image pickup device is displayed on an image monitor disposed at a position where the monitor can be viewed from the driver seat.