A 37-year-old man was diagnosed with rheumatoid arthritis, and had been treated with methotrexate, steroid, and biologics. In April 2018, a mass in the left lower lobe of the lung was detected during a medical examination; he subsequently underwent thoracoscopic partial resection of the left lower lobe of the lung for definitive diagnosis. Pathological examination revealed rheumatoid lung nodules. Six months after surgery, the patient developed a left-sided pneumothorax. Although lung sutures resulted in recurrence, the patient finally improved following endoscopic bronchial occlusion with an Endobronchial Watanabe Spigot (EWS^®). Intraoperative and postoperative management of pneumonectomy in patients with rheumatoid arthritis undergoing treatment with multiple drugs should be carefully monitored, considering the possibility of tissue vulnerability and delayed wound healing due to the drugs.