Abstract: To prevent erroneous tracking of a false target, increase reliability of target tracking, enhance continuous tracking of a real target, and thereby prevent erroneous target recognition and improve the recognition accuracy, a target is tracked on the basis of detection information that is included in detection information obtained at a plurality of different measurement time points and is estimated to have resulted from one and the same reflector; tracking reliability indicating a likelihood that a target currently being tracked has resulted from one and the same reflector is determined; and a recognition condition required for recognizing a real target is set according to the tracking reliability or its change.