1. An object detection apparatus which detects a specific object in an input image, the object detection apparatus comprising: specific object detection means for performing a specific object detecting process of setting the input image or a reduced image of the input image as a target image, and of determining whether or not the specific object exists in a determination region while scanning the determination region in the target image or an edge feature image of the target image, wherein the specific object detection means includes determination means for determining whether or not the specific object exists in the determination region, based on an edge feature amount of the edge feature image corresponding to the determination region, and a previously determined relationship between an edge feature amount and a weight indicating object likelihood for each predetermined feature pixel in an image having the same size as the determination region.