This study was conducted to investigate a correlation of factors that have an influence on the happiness of college students, and to investigate the effect of factors on happiness of college students by analyzing the structure of influencing factors of happiness. To this end, 430 freshmen in college were selected and tested on character, self-esteem, self-leadership, and happiness. The measurement tools used in this study were the 30 questions of Character Scale that Choi Min-Soo and Im Eun-Young(2013) developed and modified by Im Eun-Young(2015), a Self-Leadership Scale of Manz(1998) classified into behavioral strategy and cognitive strategy that Wang Ji-Seon(2011) translated and modified. a Self-Esteem Scale(SES) of Rosenberg(1986) that the researcher modified and used, and The Oxford Happiness Questionnaire of Hills and Argyle(2002) that Choi Yo-Won(2002) translated and the researcher modified. According to the research result, for correlation with happiness, self-esteem was .86, self-leadership was .74, and character was .66, and for correlation with self-leadership, character was .70, self-esteem was .66, and correlation between character and self-esteem was .57. Secondly, for direct effect on happiness, self-esteem was .62, character as .20, self-leadership was .19, and for direct effect on self-leadership, character was .49 and self-esteem was .38. Thirdly, indirect effect of character on happiness through self-leadership was .94 and indirect effect of self-esteem on happiness through self-leadership was .73. Through these research results, it was identified that character, self-esteem, and self-leadership of college students are the influencing factors on happiness, and that self-esteem is the biggest influencing factor on happiness of college students among the three variables. The results of this study suggested that university students' personality had a positive relationship with self-esteem and that university students' personality, self-esteem, and self-leadership altogether had a direct influence on happiness. Moreover, both personality and self-esteem of university students had an indirect influence on happiness through their self-leadership.