Foreign exchange reserves play a crucial role in maintaining macroeconomic stability, particularly in supporting smooth international transactions and sustaining market confidence. The fluctuations in Indonesia's foreign exchange reserves over the past two decades highlight the need to analyze the factors influencing these dynamics. This study aims to examine the effects of Foreign Direct Investment (FDI), Exports, External Debt, and Inflation on Indonesia's Foreign Exchange Reserves from 2004 to 2023. The analytical method used is multiple linear regression with the Ordinary Least Squares (OLS) approach, utilizing EViews software. Comprehensive testing was conducted through classical assumption tests (multicollinearity, heteroscedasticity, autocorrelation, and normality), partial significance test (t-test), simultaneous test (F-test), and the coefficient of determination (R²). The t-test results show that the variables of Exports (Prob. = 0.0151), External Debt (Prob. = 0.0047), and Inflation (Prob. = 0.0399) have a significant effect on Foreign Exchange Reserves, while the FDI variable (Prob. = 0.8710) has no significant effect. The F-test indicates that all independent variables jointly have a significant effect on Foreign Exchange Reserves, with an R-squared value of 0.944, indicating that 94.4% of the variation in foreign exchange reserves can be explained by the four variables.