In an object detection apparatus, a first association unit associates, based on radar information and camera information, radar objects with at least one camera object that are estimated to be the same as each other. If camera objects are detected so that the camera information includes at least the detection point and the type of each of the camera objects, a determination unit determines whether the camera objects express a common object in accordance with the camera information. A second association unit defines, upon determination that the camera objects express the common object, the camera objects as a camera object group, and associates, if one of the camera objects constituting the camera object group is associated with a target radar object that is one of the radar objects, all the camera objects constituting the camera object group with the target radar object.