A 75-year-old man complained of sputum and was referred to our department. His sputum cytology was class III. Chest X-ray and computed tomography showed no abnormalities, but bronchoscopy revealed an elevated lesion in the membranous portion of the left main bronchus, which was pathologically diagnosed as squamous cell carcinoma in situ. Since bronchoscopy revealed no other lesions in the visible parts of the airway, it was considered to be a solitary, early lung cancer, and sleeve resection of the left main bronchus was performed. The postoperative pathological diagnosis was squamous cell carcinoma in situ, pTisN0M0, stage 0. In recent years, an increasing number of studies have reported photodynamic therapy and brachytherapy for the treatment of early lung cancer. However, aggressive bronchoplastic surgery with emphasis on curability should be considered for lesions that are deemed resectable based on their number and extent of invasion.