An object detection device, which detects objects upon a road surface, comprising: a stereo camera for capturing images of the road surface and a road shoulder and generating image data; a three-dimensional data generation unit for using the image data generated by the stereo camera to calculate disparity data for pixels in the image data; a shoulder structure detection unit for using the disparity data and/or the image data to detect a predetermined structure (102~104) installed on the road shoulder, wherein the predetermined structure is a structure that extends in a line-of-sight direction of the stereo camera; a road surface position estimation unit for estimating a height of the road surface; and an object detection unit for detecting an object on the road surface by using the height of the road surface estimated by the road surface position estimation unit, characterised in that the shoulder structure detection unit is adapted to use the disparity data and/or the image data to search for a predetermined pattern, to detect the structure (102~104) installed on the road shoulder; the object detection device further comprises a database in which a height of the structure is stored and a structure ground-contact position derivation unit adapted to use disparity data of the structure and the height of the structure stored in the database to derive a ground-contact position of the structure (102~104) detected by the shoulder structure detection unit; the road surface position estimation unit is adapted to use the ground-contact position of the structure to estimate the height of the road surface for each position in a line-of-sight direction of the stereo camera; and the object detection unit is adapted to detect the object on the road surface by using the disparity data generated by the three-dimensional data generation unit and the height of the road surface estimated by the road surface position estimation unit to separate disparity data corresponding to the road surface and remaining disparity data other than said disparity data corresponding to the road surface from among the disparity data generated by the three-dimensional data generation unit. a stereo camera for capturing images of the road surface and a road shoulder and generating image data; a three-dimensional data generation unit for using the image data generated by the stereo camera to calculate disparity data for pixels in the image data; a shoulder structure detection unit for using the disparity data and/or the image data to detect a predetermined structure (102~104) installed on the road shoulder, wherein the predetermined structure is a structure that extends in a line-of-sight direction of the stereo camera; a road surface position estimation unit for estimating a height of the road surface; and an object detection unit for detecting an object on the road surface by using the height of the road surface estimated by the road surface position estimation unit, characterised in that the shoulder structure detection unit is adapted to use the disparity data and/or the image data to search for a predetermined pattern, to detect the structure (102~104) installed on the road shoulder; the object detection device further comprises a database in which a height of the structure is stored and a structure ground-contact position derivation unit adapted to use disparity data of the structure and the height of the structure stored in the database to derive a ground-contact position of the structure (102~104) detected by the shoulder structure detection unit; the road surface position estimation unit is adapted to use the ground-contact position of the structure to estimate the height of the road surface for each position in a line-of-sight direction of the stereo camera; and the object detection unit is adapted to detect the object on the road surface by using the disparity data generated by the three-dimensional data generation unit and the height of the road surface estimated by the road surface position estimation unit to separate disparity data corresponding to the road surface and remaining disparity data other than said disparity data corresponding to the road surface from among the disparity data generated by the three-dimensional data generation unit.