The maintenance system of tide gates (including lock gates & sluice gates), storm-surge gates and drainage pump stations, which are very important as coast line preserving facilities, is not well established yet and also not mentioned in the standards books available at present.
　For this reason, the officers working on the field stations often depend their work on the standards mentioned in the similar kind of work or play by ear according to his or her experiences. Therefore, it is very important to establish the maintenance system prevailing to this field.
　From this point of view, this thesis tries to analyse and study, in the first chapter, the actual conditions concerning to all of the tide gates mentioned above, based on the survey conducted in December, 1987. In the last chapter, based on that study, a proposal is made for maintenance system of tide gates.