In a process for producing a planar body of an oxide single crystal with a &mgr; pulling-down method, a shoulder portion having a larger width is grown without any polycrystal regions, cracks or crystal deteriorations in a central portion of the planar body. A raw material of the oxide single crystal is melted in a crucible. A seed crystal is contacted to a melt of the raw material near an opening of a nozzle 13 of the crucible. Then, the melt 18 is drawn from the opening by pulling down the seed crystal to form a planar body 14A. A temperature distribution of the nozzle 13 in a direction perpendicular to the drawing direction B is controlled by supplying heat to the nozzle 13 and/or by removing heat from the nozzle 13.