Recently, Information System (IS) development projects such as the next generation IS project of the financial business domain have shown tendency to become large and complex. Accordingly, a large number of enterprises have introduced a Project Management Office (PMO) to successfully manage multiple complex large-scaled projects. Many researches and empirical studies have proved the positive results of PMO-based projects. For example, most PMO-based projects have been accomplished successfully without exceeding the planned deadline and budget. However, even in the case of PMO-based projects, participants are still supported by legacy Project Management Systems (PMS) developed without considering the PMO. It implies that recent large projects are hardly performed efficiently because of the large gap between the legacy PMS tools developed only for single small projects and the real process of PMO-based project management. Therefore, we attempt to design and develop a PMO-based PMS in which the role and responsibility of PMO are completely implemented. To demonstrate our systems practicality, we applied the devised system to the real project management cases of "K" bank in The Republic of Korea. According to the results of case analysis, all of the four projects supported by our PMO-based PMS have been completed without exceeding planned deadline and budget, and the quality of their final outcome is appraised to be superior.