Nepal stock Exchange is the only stock market of Nepal. This study examines the effect of the independent variables on investment decision making behavior of individual in stock market. This study has used primary data to investigate the effect of the independent variables on investment decision making behavior of individual in stock market of Nepal. The data related to the study was collected from the investors present in broker house which was used for calculating the correlation and regression. This study has used both descriptive and inferential analysis. Correlation Test has found that all the independent have positive relationship except psychological factor has negative relationship. Regression analysis has found that only social interaction and regulatory policies has significant effect on investors decision making behavior for overall investors while regression analysis for beginners investors has shown psychological factor, social interaction, regulatory policies and firms image has significant effect on investors decision making behavior and for experienced investors only social interaction has significant effect on investors decision making behavior.As a whole, the study of the topic has made us understand the behavioral aspect of people while investing in Nepalese stock market.