Background: This study was conducted to identify the factors that affect the health-related quality of life (HRQoL) of middle-aged men with metabolic syndrome (MetS) based on their stress level using data from the Korea National Health and Nutrition Examination Survey (KNHANES). Methods: The participants of this study were men aged between 40-64 with MetS who were included in the KNHANES. The main variables of this study were HRQoL, which was measured using the EuroQol-5 Dimension (EQ-5D); general characteristics, health-related characteristics, and dietary behaviors. Results: The subjective health of the group with less stress was significantly better. Compared to the unhealthy group, the groups perceived as healthy and normal had a higher HRQoL. The economic level, suicidal ideation, and dinner arrangement (presence of family) of the stressed group were significantly associated with their HRQoL. Compared to a low economic level, the high and middle economic levels were more associated with the subjects' HRQoL. Compared to the group without suicidal ideation, the group that experienced suicidal association had a lower HRQoL. Compared to the group that did not dine with their family, the group that dined with family had a higher HRQoL. Conclusions: The results of this study expand the scientific understanding of HRQoL based on stress among middle-aged men with metabolic syndrome. Since differences in the influence of the factors that affect HRQoL were identified based on the level of stress experienced, the stress level of middle-aged men should be considered when devising an intervention strategy to improve their HRQoL.