Purpose: The purpose of this study was to identify the variables that affect nursing competency of nurses working in nursing homes. Methods: The participants in this study were 78 nurses who worked at 70 nursing homes in Daegu or Gyeongbuk area. Data were collected from Dec 23, 2008 to Feb 6, 2009. Descriptive statistics, independent t-test, one-way ANOVA, Pearson's correlation, and Stepwise multiple regression were used to analyze the data. Results: The nursing competency of the nursing home nurses was positively correlated with professional self-concept and nursing-role satisfaction but negatively correlated with stress. The variables affecting nursing competency in these nurses including professional self-concept, nursing-role satisfaction, Job position, and stress. These variables accounted for 42.4% of the variance in nursing competency. Conclusion: In order to improve nursing competency of nursing home nurses, a professional self-concept needs to be enhanced. A specific strategy would be to improve the nursing environment and reduce nurses' stress in order to increase nursing-role satisfaction.