The impact of COPD severity on labor force participation and work loss is not well known. This study aimed to describe the characteristics of occupations and to evaluate the reason for work loss based on the severity of airflow obstruction (AO). We performed a cross-sectional study using data from the Korean National Health and Nutrition Examination Survey V-VI. We identified 9,901 people aged 40 to 60 years who had normal or AO in spirometry test results. AO was defined as a pre-bronchodilator forced expiratory volume in 1 second/forced vital capacity <70%. AO was present in 7.6% of the subjects, and 81.5%, 82.9%, and 71.6% of subjects with mild, moderate, and severe-to-very severe AO were in the labor force, respectively. Multivariable analyses revealed that severe-to-very severe AO subjects were more likely to have precarious job (adjusted OR = 4.71, 95% CI = 1.70-13.06) and cite health-related problem as the reason for not being in the labor force (adjusted OR = 3.38, 95% CI = 1.03-11.02). Overall, AO was not associated with any significant changes in labor force participation. However, subjects with severe-to-very severe disease were more likely to drop out of the labor force owing to their health-related problems.