The purpose of this study is to examine the effect of the regret factor on risk-taking behavior and to show the relationship between affective factors, cognitive factors, personality factors, and risk-taking behavior. In the experiment, undergraduates ( N = 60) completed a questionnaire on affective factors (regret and anxiety), cognitive factors (own perceived competence, risk perception, risk controllability, and perceived cost), personality factors (Five Factor Model: neuroticism, openness, extroversion, agreeableness, and conscientiousness), and risk-taking behavior in personal gain-loss situations (skiing, gambling, and an entrance examination), personal loss situations (jaywalking, prevention against theft, and credential acquisition for protection against unemployment), and social situations (approval of the construction of a nuclear power station and disaster plans for earthquakes). Results of covariance structure analysis showed that personality factors influenced risk-taking behavior by the path of affective factors and the path of cognitive factors: (a) neuroticism affects risk-taking behavior mediated by anxiety and regret, (b) openness affects risk-taking behavior mediated by own perceived competence and risk perception. In all situations, the regret factor influenced directly risk-taking behavior and the anxiety factor influenced risk-taking behavior mediated by the regret factor. These facts indicate that the affective factors affect decision making in all risk-taking situations.