This study examined the relationship among social support, stress and coping behavior among 376 students(154 students depending on internal locus of control and 122 students depending on external locus of control). Using the covariance structure modeling(LISREL-VIII), the relationship among three constructs were investigated, There was a significant direct effect of social support on coping behavior and indirect effect through stress situation. Also, social support had a significant direct effect on stress and stress variable had a direct effect on coping behavior. In other words, it was founded that social support is used to coping behavior as coping resource as well as relax that as effect to evaluation and cognition to stress situations. This result is support to stress appraisal model by Cohen, Wills(1985) & Lazarus, Folkman(1984). Causal relationship of each variables was not difference depending on internal-external locus of control. This result is consistent with studies that deny personality variable about effect of social support recently. A men eveluate to social support and stress situations regardless of depending on internal-external locus of control and that evaluation was founded that important variable to decide coping behavior.