Purpose: The purpose of this study was to identify the effects of nursing competency of nurses on job satisfaction and nursing performance. Method: Using a structured questionnaire, data were collected from 368 nurses. Descriptive statistics, t-test, ANOVA, Scheffe test and pearson correlation coefficient with SAS package were used for data analysis. Results: The total mean score for nursing competency was 2.65, with scores for subcategories as follows: ethical competency 2.74, personal competency 2.65, esthetical competency 2.64, and scientific competency 2.61. The mean score of total job satisfaction was 3.18 on a 5 point scale, and nursing performance was 2.97 on a 4 point scale. Total nursing competency and total subcategories of nursing competency perceived by nurses were positively related to job satisfaction and nursing performance. Conclusion: In conclusion, nursing competency of nurses influence job satisfaction and nursing performance. With these result, it is necessary to concentrate on improving nursing competency of nurses to increase job satisfaction and nursing performance.