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 said image; an obstacle determination device that determines whether or not another body being an obstacle is present between said infrared imaging device and said binarized object extracted by said binarized object extraction device; a height calculation device that calculates a height dimension of said binarized object based on the height dimension of said obstacle on said gray scale image when it is determined that an obstacle is present in a determination result of said obstacle determination device; and an object type determination device that determines a type of said object based on the height dimension of said binarized object calculated by said height calculation device.