Behavioral finance is a multidisciplinary subfield of finance dealing with behavioral / psychological implications of financial decision making. Even though the psychological and sociological phenomena that affect human behavior are widely discussed in terms of behavioral science, their impact is relatively new in the area of finance. This study?s main objective is to discover how individual investors behave and make financial decisions from the behavioral finance point of view. In the study, survey-based study about the irrationality of individual investors when trading is exhibited. According to the test results, biases categorized under self deception have stronger impacts and therefore investors are suffering from their cognitive disabilities. Males tend to have more biases than females in terms of gender and common behavioral biases relationship. Mental accounting, representativeness, cognitive dissonance and confirmation biases tend to increase as education level increases; on the other hand, illusion of control and ambiguity aversion have negative correlation with education when the relationship between education level and common cognitive biases is concerned.