The purpose of this study was to compare the psychological traits of middle school students without disabilities according to their status of siblings with developmental disabilities. The participants were 27 middle school students with developmental disability siblings and 29 middle school students without developmental disability siblings living in Busan and Gyeongsangnam-do. The collected data were analyzed by using descriptive statistics, t-test. The results were as follows. First, as a result of comparing the personality traits of the middle school students without disabilities according to their status of siblings with developmental disabilities, it was found that ‘responsibility and ’confidence’ showed a significant difference, but it was found that ‘stability’, ‘extroversion’ and ‘directedness’ showed no significant difference. Second, as a result of comparing the emotional traits of the middle school students without disabilities according to their status of siblings with developmental disabilities, it was found that ‘depression regulation’ showed a significant difference, but it was found that ‘anxiety regulation’, ‘self-assertiveness’, ‘life satisfaction’ and ‘interpersonal ability’ showed no significant difference. Third, as a result of comparing the maladaptive traits of the middle school students without disabilities according to their status of siblings with developmental disabilities, it was found that ‘stress index’ and ‘other-consciousness’ showed a significant different, but it was found that ‘acting-out tendency’ showed no significant difference.