A stereo-image recognition unit detects a pedestrian from a solid body acquired from the image by a stereo camera and issues various warnings by outputting signals to an LED and a speaker according to the position of the pedestrian, the vehicle speed, and a signal from a turn signal switch. The unit determines whether the solid body approaches a predetermined region in the image, with one end of the solid body in the width direction being detected and the other end not being detected, and detects the width of the solid body when the other end is detected. The unit then determines whether the solid body is a pedestrian by comparing the width with a predetermined threshold. Accordingly, the unit can rapidly and reliably detect a pedestrian who approaches the vehicle traveling route and inform a driver of it and reduce an operation load necessary for detecting a pedestrian.