Elevator accidents are becoming an issue of public concern. To cope with these circumstances, assurance of safety by the mutual complementarity of design and maintenance of elevators is crucial. This paper summarizes some elevator accidents and discusses assurance of elevator safety by the mutual complementarity of design and maintenance, as well as concrete approaches to it. If maintenance has not been carried out properly, safety of the elevator is not ensured. And even if the proper maintenance is carried out, if the design is not safety design, safety is not be ensured as well. Safety of the elevator is achieved by the mutual complementarity of both the design and maintenance. The system safety management in recent years, design and maintenance has been carried out on the basis of the risk assessment, and consideration from the point of view of life cycle is also important. The elevator design presupposed maintenance, it is necessary to ensure safety throughout the life cycle by the mutual complementarity of safety design and maintenance.