[Purpose] The purpose of this study was to investigate differences in effects caused by variation in the intervention frequency of outpatient pulmonary rehabilitation, in terms of the pulmonary function, lower-limb muscle strength, exercise tolerance, and quality of life (QOL). [Subjects and Methods] A total of 36 patients with mild to severe chronic obstructive pulmonary disease (COPD) were studied. These patients were all men over the age of 40 who did not require assistance for activities of daily living (ADL). Groups undergoing intervention once a month (M1 group) and once a week (W1 group) were compared in terms of the effects of outpatient pulmonary rehabilitation for a period of 12 weeks. Intervention during this time included supervised and home-based exercise. [Results] Comparison of before and after intervention revealed that the rate of change in the W1 group was significantly higher than that in the M1 group in terms of the QOL, lower-extremity muscle strength, and 6-minute walking distance. [Conclusion] Outpatient pulmonary rehabilitation programs yielded greater improvements in the W1 group than in the M1 group in terms of the QOL and exercise tolerance.