With recent growth of the economy and development of construction technology, the increase of high-rise buildings is appearing rapidly in urban areas. For this reason, the interest in building maintenance has also been increasing. However, it has many safety problems because it is difficult for the workers to access the exterior wall of building. Therefore, the maintenance system of high-rise building stands out as being important issues to be developed, so that a variety of robot systems have been developed to accomplish the building-wall maintenance works. In this paper, the maintenance robots are classified in painting, inspecting, cleaning systems according to the maintenance works. Then, their locomotion and adhesion mechanisms are analyzed including their applicability to the real maintenance works. This study can be used to develop maintenance robotic system that is more efficient and stable than existing ones.