The concept of risk in investment and individually risk taking and risk aversion is one of the important concepts in managing capital and investing. Different people have different levels of risk taking. From the psychological point of view, individuals can be classified into different personality types, and different types may have a different risk-taking approach to investing. The purpose of this study is to examine the relationship between the five great factors of personality with the risk preference. For this purpose, the required information was collected by sending a questionnaire to 202 people who were selected in a accessible manner among all active investors in Tehran Stock Exchange. To test the hypotheses, Pearson correlation and regression were used. Findings showed that Openness to Experience individuals tend to accept more risk and Conscientiousness individuals tend to accept less risk. Regression analysis showed that among big five factors of personality, conscientiousness (β=-0.20) and emotional instability neuroticism (N) (β= 0.17) is significant in model regression criterion. The results also show that gender, years of experience in investing, age, field of study, and have no significant effect on risk aversion level. The results of this research can be used to understand the financial behavior of investors and predict their behavior.