To establish an operational ocean forecasting system, an operational data management system should be established concurrently to manage systematically oceanographic data and information related to the marine forecasting. In the last year, new operational data management system of KOOS (Korea Operational Oceanographic System) was planned to collect new oceanographic data as the input data of ocean models and provide the forecasting information to the data users. The system is composed of 2 sub systems, the one is the data management system which handles newly collected observation data and ocean model output, the other is the data providing system which distributes forecasting information to the general public and the ocean experts (Figure 1). As the first step of developing the operational data management system, a data archiving system was set up and started to be operated.