Though robots are lifeless objects, they appear to be agents with capacities to perception, judgment, and action, which make them unique to the philosophical viewpoint. Intelligent robots would play the role of various forms of surrogate of human agents, which implies their irreplaceable utility and unique risk at the same time. They are even told to be artificial moral agents. This paper discusses the question of what normative principles are to be applied when we deal with such unique artefacts, thereby suggests a set of basic principles of robot ethics. For this purpose, it investigates the ontology of robot. It reveals that a robot is physical realization of externalized mind, of its designers, manufacturers, and administrators. In order to deal with the risk of such intelligent artefacts, it is of highest importance to retain the clear context of human control over them. This requires further that the purpose, functions, and relevant properties of the robotic system be explicitly defined and consistently observed through all the processes of its manufacturing, maintenance, and application. Another part of the basic principles of robot ethics concerns the principle of sustainability.