The purpose of this study was to investigate the personality traits in three constitutional types, So-yang, So-eum and Tae-eum, using NEO-PI-R. The Questionnaire for QSCC II and NEO-PI-R Korean version were completed by 155 university students (108 males and 47 females), Analysis of difference among groups was conducted by ANOVA and followed by Scheffe test. Significant differences of personality among three constitutional types were revealed with respect to NEO-PI-R scales such as Extroversion and Openness in the big five factors and Anxiety, Angry ,Gregariousness, Assertiveness, Excitement Seeking, positive Emotion, Fantasy, Feeling, Action, Values, Modest and Deliberation in subtypesof the big five factors. The score of So-yang is significantly higher than that of so-eum in Extroversion, Openness, Angry, Gregariousness, Assertiveness, Excitement Seeking, Positive Emotion, Fantasy, Action and Values. The score of So-yang is significantly higher than that of Tae-eum in Extroversion, Openness, Gregariousness, Assertiveness, Excitement Seeking, Feeling, Action and Values. The score of So-eum is significantly higher than that of So-yang in Anxiety, Modest and Deliberation. The results Suggst that NEO-PI-R is helpful to determine constitution type, especially in the level of personality.