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 image of the image; a region setting device that sets a region including the binarized object extracted by the binarized object extraction device on the gray scale image; a luminance status quantity calculation device that calculates a luminance status quantity of the region set by the region setting device; a luminance distribution determination device that determines whether or not a predetermined luminance distribution exists in the region based on the luminance status quantity calculated by the luminance status quantity calculation device; and an object type determination device that determines a type of the object based on a determination result of the luminance distribution determination device.