An object detection apparatus mounted in a vehicle for detecting a target object in various changing environmental conditions. In the apparatus, a storage prestores plural image recognition dictionaries each describing reference data for the target object, and plural image recognition techniques each used to detect the target object from an input image with use of one of the plural image recognition dictionaries. A first acquirer acquires an operating state of a lighting device of the vehicle. A selector selects, according to the acquired operating state of the lighting device, one of the plural of image recognition dictionaries and one of the plural of image recognition techniques. A detector detects the target object in the input image by applying image recognition processing thereto with use of the selected image recognition dictionary and technique.