The purpose of this study is to investigate the structural relationship between psychological distress, interpersonal relationship competency, social support perception, and cognitive flexibility of late adolescents. To this end, an online survey was conducted on male and female college students nationwide, and the structural relationship of the data of 469 people was finally analyzed. As a result of the study, first, it was found that all variables had statistically significant correlation. Second, it was found that both the path of psychological distress to interpersonal relationship competency through social support perception and cognitive flexibility, and the path to interpersonal relationship competency through cognitive flexibility and social support perception were significant. Third, as a result of verifying the mediating effect between the main variables, it was confirmed that the simple mediating effect and the sequential mediating effect were significant. Based on the research results, it was suggested that there is a need to find a way to reduce psychological distress and improve interpersonal relationship competency in terms of social support perception and cognitive flexibility of late adolescents.