MgO nanosheets possessing the (111) facet as the main surface were synthesized and the Ni catalyst supported on MgO(111) nanosheets was investigated for the carbon dioxide reforming of methane. The catalytic activity and carbon deposition were compared between Ni/MgO(111) and Ni/MgO(commercial) catalysts. The results showed that Ni/MgO(111) performed at a higher activity as well as a longer stability. From the characterization results, the improved catalytic performances of Ni/MgO(111) were suggested to be closely associated with both the high dispersion of active Ni particles owing to the strong metal-support interaction and the large amount of basic sites of MgO(111) due to its unusual surface properties.