Objectives: The aim of this study was to elucidate the effect of illness and unhealthy behavior on early retirement due to health problems (ERdHP) using Korean longitudinal data. Methods: This study used data collected from 3,508 subjects enrolled in the first to fourth phases of the Korean Longitudinal Study of Ageing (KLoSA). This study was conducted from 2006 to 2012 using structured questionnaires on retirement, morbidities, and health-related behaviors. We adopted the Cox proportional hazard model to investigate the effects of diagnosed disease and health-related behaviors on ERdHP. Results: Participants who smoked, were obese, or suffered from hypertension, diabetes, malignancy, heart disease, stroke, or arthritis had a significantly higher risk of health-related early retirement after adjustment for gender, age, and occupation. Further, risk factors such as lack of exercise, stroke, arthritis, obesity, and malignancy differentially affect early retirement by gender. Conclusions: This is the first study, that we are aware of, to examine the effect of illness and unhealthy behavior on ERdHP in Asia, using Korean longitudinal data. We found that hypertension, diabetes, malignancy, arthritis, cardiovascular and cerebrovascular diseases, smoking, and obesity increased the risk of ERdHP. To enhance the sustain ability of labor in an aging society, more studies on ERdHP are needed.(J Occup Health 2015; 57: 28–38)