The purpose of this study was to examine the relationship between adult attachment, adjustment to college life, and interpersonal competence in nursing college students and investigate whether or not interpersonal competence mediates the relationship between adult attachment and adjustment to college life. The subjects of this study were 685 college students located in J-si and M-si, and data were collected for 25 days from November 1 through 25, 2015. The collected data were analyzed by t-test, Pearson correlation coefficients, Hierarchical regression, and Sobel test using SPSS 23.0. As adult attachment increased, adjustment to college life was enhanced (B=.225, p=.027); as interpersonal competence increased, adjustment to college life improved (B=.145, p=.040); and as adult attachment increased, interpersonal competence increased (B=.396, p=.021). In addition, interpersonal competence significantly mediated the relationship between adult attachment and adjustment to college life (Z=3.560, p<.001). To enhance adjustment to college life in nursing college students, adult attachment and interpersonal competence need to be improved.