This paper is designed to analyze the sustainability of the central government budget in the case of Indonesia over the periode of 1999-2009. First we explore the theoretical background of the fiscal sustainability. Second we develop a model to capture some factors determining the fiscal sustainability. Unlike the previous studies we use both domestic debt and foreign debt to assess the fiscal solvency. Finally we estimate it empirically. based on the quarterly data analysis we concluded that the government budget is unsustainable. This is associated with domestic debt rather than foreign debt. They imply that the central government should manage the debts carefully including re-profile re-schedule and re-structure them in order to spread the excess burden in the future. Also the fiscal risks should be calculated comprehensively in order to maintain solvency.