Investment has become need in the society, it is no longer wants. The society need higher gain in shorter time period. The millennial generation is the largest population at a productive age and plays an important role in investing. However, many of them are still not getting their investment result as they expected. Therefore, there are many factors that must be considered by every investor in order to avoid the risks that may arise to losses in investing. This phenomenon was suspected because the millennial investors are still lack of financial literacy, risk management, reckless financial behavior, and overconfidence on investment decisions. Based on this, the main focus and purpose of this research is to evaluate and analyse the effect of financial literacy, risk perception, financial behavior, and overconfidence on investment decisions in the millennial generation in the Jakarta area to give ideas for the millennial investors and practitioners in making decision to invest. This paper fills a literature gap by testing the financial literacy as a moderator in the relationship of financial behavior, risk perception and overconfidence toward investment decision. The study utilized a quantitative survey of 200 millennial investors in Jakarta, and the data is analyzed using PLS-SEM. This study finds that financial behavior, overconfidence, risk perception has positive effect on investment decisions is accepted, which means that financial behavior affects investment decisions for millennial generation in Jakarta. The result also finds that financial literacy moderates the effect of financial behavior and overconfidence on investment decision, but it cannot moderate risk perception on investment decision. The findings in this study will assist the investors get the ideas in making decisions to invest it is likely to be influenced by these three factors. Moreover, financial literacy can moderate the effect of financial behavior and overconfidence on investment decisions. The role of financial literacy as the moderation variable can give the investors insight that financial literacy is something they should prioritize because financial literacy plays a huge role in controlling investors' irrational behavior in decision-making.