Purpose: The aim of this research was to identify the mediating effect of sleep quality on the relationship between job stress and stress response of shift-working nurses. Methods: The participants in this study were 150 nurses who had more than 6 months of shift-working experience. A survey was conducted from May to June 2017 in a hospital in Gyeonggi-do, South Korea. The data were collected through self-report questionnaires. The collected data were analyzed using SAS 9.4 program. The analysis was based on Baron and Kenny’s model to examine the mediating effects of sleep quality on the relationship between job stress and stress response of shift-working nurses. Results: In the first and second steps, job stress was identified as a significant predictor of sleep quality (β=.29, p=.001) and stress response (β=.24, p=.004). In the third step, sleep (B=.55, p<.001) was observed as a significant predictor of stress response, and the direct relationship between job stress and stress response was not significant (β=.07, p=.291). Sleep quality was found to exhibit complete mediating effect on the relationship between job stress and stress response. Conclusion: The results of this study suggest that strategies for managing the stress of shift-working nurses should include effective ways to ensure sleep quality.