An object detector includes a brightness change calculating section (103) that calculates the change in brightness in an image, a three-dimensional object detecting section (105) that uses three-dimensional information measured from a plurality of images to detect a three-dimensional object, an object candidate extracting section (106) that refers to the three-dimensional object detection results and the brightness change calculation result to extract a moving object candidate area and a still object candidate area, and an object judging section (107) that judges whether or not the candidate area is an object. In this way, the object detector refers to the change in brightness in the area detected as a three-dimensional object to judge whether the detected three-dimensional object is a moving object or a still object. Therefore, a still object in the image can be accurately detected without using background difference processing.