Purpose: The purpose of this study was to analyze the effects of self-efficacy and collective-efficacy on job stress in the nursing staff. Method: This study surveyed 160 nurses in three general hospitals in the Seoul and Gyung-gi province for two months starting in September 2004. The questionnaire consisted of 54 questions about job stress, 10 questions about self-efficacy, and 7 questions about collective-efficacy. The answers were on a scale rating of 5. The answer sheets were analyzed with descriptive statistics, the t-test, ANOVA, the tukey test, the Pearson correlation coefficients and stepwise multiple regression using SAS version 8.2. Result: The average job stress rating of the nurses was 3.11. The average self-efficacy and the average collective-efficacy were 3.41 and 3.39, respectively. The age, working department, income level, shift-work and hospital have influence on job stress. Efficacies such that self-efficacy and collective-efficacy have influence on job stress. The much efficacy makes the less job stress. The stepwise multiple regression revealed that the significant predictor of job stress was working department and hospital. Conclusion: This study showed that collective-efficacy as well as self-efficacy reduces job stress, so nursing intervention methods should promote collective-efficacy. The collective-efficacy improvement program should be developed to improve job performance, to improve cohesion of nursing units, and to improve satisfaction on the job. The next research could be to develop collective-efficacy improvement programs for nursing units.