An object detection apparatus is provided with: an imager configured to image surroundings of a subject vehicle and to obtain a surrounding image; an object detector configured to detect an interested-object from the surrounding image and to output first image coordinates, which indicate a position of the detected interested-object on the surrounding image; a calculator configured to associate the interested-object with one or more coordinate points out of a plurality of coordinate points, each of which indicates three-dimensional coordinates of respective one of a plurality of points on a road, on the basis of the first image coordinates and a position of the subject vehicle, and configured to calculate at least one of a position of the interested-object on a real space and a distance to the interested-object from the subject vehicle on the basis of the position of the subject vehicle and the one or more coordinate points associated.