The purpose of this study was to examine the effects of new graduate nurses’ self-leadership, organizational socialization, and preceptors’ communication style on clinical competency in order to improve their clinical competency. A total of study subject were 123 nurses who had worked for less than 12 months of clinical experiences at an advanced general hospital in J city. The collected data were analyzed using frequency percentage, mean, standard deviation, independent t-test, one-way ANOVA, Pearson’s correlation coefficient, and stepwise multiple regression analysis by SPSS/WIN 27.0 program. There were no significant differences between new graduate nurses’ general characteristics and clinical competency(F=1.01, p=.390). The factors affecting new graduate nurse’s clinical competency were self-leadership (β=.59, p<.001), and organizational socialization-job satisfaction (β=.15, p=.046), explaining 45.1% of the variance (F=49.24, p<.001). Based on the results of this study, the effective education program is needed to enhance new graduate nurses’ positive self-leadership as well as to increase job satisfaction in order to better perform clinical competency.