This study examined the effects of individual difference and situation on risk taking behavior. In Experiment 1, 115 undergraduates completed a questionnaire of personality (sensation seeking, optimism, etc.) and their risk taking behavior, risk perception, and anxiety in eight situations: personal, social, gain-loss, and loss situations. Results indicated an effect of personality on risk taking behavior in personal gain-loss situations (sports and life event), which was mediated by perceived risk controllability. In Experiment 2, 137 undergraduates completed a questionnaire of personality, cognitive variables (risk perception, own competence, and perceived cost and benefit), and risk taking behavior in personal gain-loss situations (sports, life event, and gambling). Results of covariance structure analysis showed that perceived risk controllability affected the relationship between the variables. For instance, risk significance and perceived cost and benefit mediated the effect of 'controllability with skills' on risk taking behavior in the controllable situation (e.g., sports). Similarly, competence and risk perception mediated the effect of 'uncontrollable luck factors' in the chance situation (e.g., life event).