1. A vehicle surroundings monitoring apparatus that extracts a body present in the surroundings of a vehicle as an object, based on an image captured by an infrared imaging device, comprising: a binarized object extraction device that extracts a binarized object from image data obtained by binarizing a gray scale images of the image; a search region setting device that sets a search region at the lower part of the binarized object extracted by the binarized object extraction device; a vertical edge detection device that detects a vertical edge in the search region set by the search region setting device; and an object type determination device that determines a type of object based on a detection result of the vertical edge detection device.