This study looks at the background and the process of building a management accounting system aimed at a financial company A and presents solutions for the successful settlement of management accounting system. Recently, Capital Market Consolidation Act and U.S. Free Trade Agreement(FTA) have also required to the financial industry the need for advanced management of business. In a recent situation that many financial companies are changing or building the management accounting system for the business environment. The purpose of this study is to examine the possible decision situations that can be encountered on financial company through a successful practical examples of A's management accounting system. While building a management accounting system, the major decision points are a multi-dimensional income analysis, profitability analysis for responsibility accounting unit, calculation of business cost, calculation of capital cost, calculation of profit for daily / monthly period, interface and integrity of data. On the other hand, this paper proposes the following points to make a successful settlement of management accounting system. First, documents, data, and application software should be standardized. Second, security management for the user is essential for management accounting system to operate stably. Third, if closing procedure is performed by hand, settlement calendar will be delayed. Thus, it is a need to reorganize the settlement procedure. Finally, management accounting system should be managed according to the systematic basis in order to analyze the financial statements of subsidiaries easily and shall unify the source data of management accounting and financial accounting.