An object detection apparatus includes a radar that detects the position of an object; an imaging device that detects the position and size of an object; a fusion processing device that fuses the object detected by the radar device and the object detected by the imaging device as the same object, when the detection results of the radar device and the imaging device satisfy a prescribed fusion condition, to generate a fusion object having position information and size information. A provisional fusion object is generated if the detection result from the imaging device does not satisfy the fusion condition with respect to the detection result from the radar.