AbstractThe authors have developed the tracking control system of astronomical objects in the Nobeyama millimeter array. A system was studied which can accomplish sufficient tracking accuracy for an interferometer, such as delay tracking, phase tracking, and fine delay correction. It was found that the location error of an astronomical object can be made less than 1 percent of the maximum spatial resolution on a synthesized map and the radio intensity degradation less than 0.1 percent if the phase tracking is executed at an interval of about 10 s and the fine delay correction at 1 ‐ 2 s. Further, from the actual observation results, it was confirmed that this system has realized an extremely high tracking accurac