1. An object detector for detecting an object of detection out of an input image, the detector comprising: an object detecting unit adapted to detect object candidates judged to be the object; a non-object detecting unit adapted to detect non-object candidates judged to be non-objects and output the object candidates less the non-object candidates; a distance measuring unit adapted to measure a distance between the object detector and the object of detection; the non-object detecting unit is further adapted to compute an assumed distance between the object detector and the object of detection on the basis of a size of an object candidate in the detected object candidates relative to the input image and judge the object candidate to be a non-object candidate when a difference between the assumed distance and the distance measured by the distance measuring unit is greater than a predetermined threshold value; and the non-object detecting unit is further adapted to compute, using a processor, a variance of the object candidate in a color space and, if the variance is less than a predetermined variance threshold value, judge the object candidate to be the non-object candidate.