For considering effective and rational maintenance strategies for port and harbour infrastruclures, it is important to establish a maintenance management system that will provide engineers with several altematives for maintenance work. This study attempts to develop a decision-making support system for maintenance management of existing open-piled piers based on life cycle analysis. The durability and ultimate strength are taken as the main indexes of structural performance for a concrete deck and supporting steel piles. The maintenance management system will be able to predict the future deterioration process of structural members of the piers and to suggest a maintenance plan for repair based on a combination of maintenance cost minimization and quality maximization approach. This paper describes an outline of the proposed system including some assumptions to evaluate present and future deterioration and database of repair/maintenance techniques. Also the performance of the system is verified through practical application of an existing open-piled pier. This maintenance management system will be available on a personal computer program.