The purpose of this study is to analyze the relationship between personality and major and the relationship between personality and academic achievement for unversity students. Students' personality was examined based on MBTI personality theory. According to MBTI theory, personality consists of 4 dimensions and each dimension has two contrasting preferences(extraversion / introversion, sensing / intuition, thinking / feeling, judging / perceiving). For this study, 235 students were sampled from the divisions of humanities, natural sciences, and arts in a university. MBTI test was administered to the students and information about their satisfaction with major and academic achievement was collected. The result showed that students' personality in two dimensions(extraversion / introversion and judging / perceiving) was significantly associated with the choice of majors. Meanwhile, it was found that some of personality preferences were significantly correlated with students' satisfaction with major and academic achievement. These results imply that the diagnosis of personality can be used to help university students select appropriate majors and enhance academic achievement.