More than 140 years have already passed since the opening of the first railway in Japan. During that period, a lot of railway structures were constructed. Many of them have been used for more than 100 years and are still in service. In many cases, it is necessary to continue to use those existing structures with appropriate maintenance because the replacement is difficult while in service.This paper firstly describes an outline of current status of the existing railway structures, especially steel bridges, and maintenance of them. Secondly, it introduces recent topics of research and development regarding the maintenance of the steel bridges, such as monitoring, renewal and seismic retrofit.