Surface reactivities of the three low-index planes (111), (100), and (110) of cubic boron nitride were theoretically investigated using density functional theory under periodic boundary conditions. Surface energies for non-terminated (bulk vs. optimized structure) and H-terminated (optimized structure) surfaces were calculated. The optimized structure is identical to the local low-energy structure closest to the initial bulk geometry. The adsorption process of hydrogen atoms on the various surface planes was also examined. On the basis of these calculations, the orders of reactivities for the cubic BN planes are (110)>(100)>(111) (bulk) and (100)>(110)>(111) (optimized) for non-terminated surfaces. The most reactive form of the (110) surface (i.e. bulk structure) became the most stable one when the surface was completely terminated with H species.