Purpose: This study was aimed to compare nursing competency, self-esteem, and job stress between floating nurses and clinical nurses. Methods: The data were collected between October $1^{st}$ and December $31^{st}$, 2015, from 43 floating nurses and 57 clinical nurses working at a tertiary care hospital in Seoul. The collected data were analyzed with SPSS/WIN 23.0, using descriptive statistics and the t-test, $x^2$ test, ANCOVA, ANOVA, $Scheffe{\acute{e}}$ test, Pearson correlation coefficients, and Stepwise multiple regression. Results: The nursing competency of clinical nurses was significantly higher than that of floating nurses (F=4.370, p=.039). For both floating and clinical nurses, nursing competency was positively correlated with self-esteem (floating nurses, r=.47, p=.002; clinical nurses, r=.62, p<.001). Also, For both floating and clinical nurses, the most significant predictor of nursi ng competency was self-esteem(floating nurses, ${\beta}=0.45$, p=.001; clinical nurses, ${\beta}=0.60$, p<.001). Conclusi on: Efforts are needed to increase the nursing competency of the floating nurse through the improvement of the floating system, the nursing work environment, and continuous education. Also, as self- esteem is the most effective predictor of nursing competence, nursing intervention is needed to improve self-esteem of the floating nurse.