This study aims to identify and analyze the factors that affect foreign exchange reserves in Indonesia. We consider the variables of external debt, exchange rate, inflation, and exports as explanatory factors referring to previous studies. We apply the Autoregressive Distributed Lag approach to time-series data retrieved from the Central Bank of Indonesia (BI), the Central Bureau of Statistics (BPS), and International Monetary Funds (IMF) from January 2016 to December 2018. Our results show that foreign debt, exchange rates, inflation, and exports significantly affect the simultaneous fluctuation of foreign exchange reserves in Indonesia. Partially, foreign debt has a significant and positive effect on foreign exchange reserves. The exchange rate has a significant and negative effect on foreign exchange reserves in Indonesia. However, our findings explain that inflation does not significantly affect foreign exchange reserves in Indonesia, and exports have a significant and positive effect on foreign exchange reserves. This study is expected to be useful to policymakers in managing foreign exchange reserves, so the economy of Indonesia can grow sustainably. One of the exciting things in this study lies in the model that uses the Autoregressive Distributed Log, which can explain long-term relationships through adjusted coefficient and cointegration tests.