Atomic and electronic structures of alpha-Al2O3(0001)/Ni(111) interfaces have been investigated using the first-principles pseudopotential method. Models with different rigid-body translations parallel to the interface for both the O-terminated and Al-terminated interfaces are examined in order to clarify the overall features. Results indicate that the interface stoichiometry as well as the interface configuration has significant effects on the adhesive and electronic properties. The bonding nature of the O-terminated interfaces is explained by strong ionic and Ni-3d/O-2p orbital hybridization interactions, and that of the Al-terminated interfaces is explained mainly by image-charge like electrostatic and Ni-Al hybridization interactions, although there is some Ni-O hybridization for the O-site model. Orbital hybridization and adhesive energies are larger than those in the corresponding Al2O3/CU interfaces, because Ni has higher activity for making bonds with ceramics than Cu.