Offering safe and high quality medical services and securing the employment of medical workers is essential for the success of every medical institution. Medical workers need to collaborate with other types of workers, and must engage in tasks beyond the call of duty, however, past studies have suggested that medical workers do not collaborate extensively with other types of workers. Previous studies that have investigated the quality of medical services have used various definitions of the quality of services. Here, the quality of medical services was clearly defined based on reviews of previous studies, as well as on theories of team medical care. Moreover, studies have suggested that that the high turnover of nurses was caused by the inability of nursing managers to accurately understand the reasons for the turnover. This study examined the psychological processes underlying safe, high quality services offered by nurses that continue to work in an organization, from the perspective of social identity theory and dual identity. This perspective describes the process in which "pride" in the high evaluation of group position and "respect" in the high evaluation of own position in the group strengthens group identity, which in turn promote cooperation.