This study examined the effects of environmental and planned changes in hospital organizations on employees' job stress and resistance to change, the effects of change resistance and stress on turnover intention and organizational commitment, and the multiple mediating effects of change resistance and job stress on the relationships between environmental/planned changes and turnover intention and organizational commitment. The results of this study are summarized as follows. First, environmental change was found to have a positive (+) effect on both emotional resistance and behavioral resistance. Second, planned change was found to have a positive (+) effect on job stress. Third, environmental change in hospital organizations was found to have a positive (+) effect on organizational commitment. Fourth, emotional resistance was found to have a positive (+) effect on turnover intention and a negative (−) effect on organizational commitment. Fifth, job stress was found to have a positive (+) effect on turnover intention and a negative (−) effect on organizational commitment. Finally, environmental change was found to affect turnover intention through the mediation of job stress, and planned change was found to affect organizational commitment through the mediation of job stress. By identifying the mediating role of job stress in the relationship between organizational change and job attitudes, this study provides the comprehensive implication that job stress management is of paramount importance for organizations facing change.