Studying the role of interest rate to motivate investment has seen increasing interest worldwide, especially in developing economies. However, statistics have shown that investment in Egypt has been moderate during the period (1980-2018). Study data collected from the World Bank and International Monetary Fund databases. It also ensured that the time series were made balanced and interconnected, and then the Auto Regressive Distributed Lag (ARDL) method used in the analysis. The empirical results indicate both, presence of long-run Cointegration between the investment and interest rate, and interest rate granger causes investment, which is our primary concern of this research.   The study recommends the Egyptian government reconsidering many of the general state policies, including investment policies, financial and administrative governance, and monetary policy that focuses on maintaining a balanced interest rate that improves and motivate the investment environment.