This study aimed to find out the effect of job stress of workers in elderly care facilities on job satisfaction and to verify the mediating effect of professional efficacy of specialized job in their relationship, and the results were as follows. First, the level of job stress(3.20), professional efficacy(3.51), job satisfaction(3.22) were all higher than the mean value(3.0) and among subcategories of job satisfaction, job-related human relationship was the highest and job security and growth potential were the lowest. Second, variance analysis showed that job stress was higher in the group of college graduates than in the group of middle school graduates and it was higher in the group with the monthly salary higher than 1 million won than in the group with the monthly salary of 1 million-1.4 million won. Professional efficacy was higher in the married group than in single group, among nursing staff than among social welfare workers, in facilities with the capacity of bigger than 100 people than those with the capacity of less than 50 people, and among workers who work day time than those who work every other day. Third, multiple regression analysis showed that age, the capacity of facilities, job stress, professional efficacy had a significant influence on job satisfaction, and professional efficacy had the biggest influence, which was followed by job stress, and age and capacity of facilities had relatively smaller influence. Fourth, the three-step regression analysis of Baron & Kenny revealed that professional efficacy had a partial mediating effect on job satisfaction. Such results of study strongly imply the necessity of the approach that raises job satisfaction by reducing job stress and increasing professional efficacy of workers.