We report a rare case of tracheobronchomegaly with crescent-type tracheobronchomalacia. A 77-year-old man with a chronic cough was referred to our hospital because of fever and dyspnea. Radiographic examination showed enlargement of the trachea and main bronchi. On chest radiography, the transverse diameter of the trachea was 31 mm, and consolidation shadows were seen in both upper lung fields. Tracheobronchomegaly with pneumonia was diagnosed. The pneumonia was improved by administration of PAPM/BP. On bronchoscopic examination, the trachea and main bronchi were extremely dilated on inspiration, and were collapsed on expiration. The biopsy specimen from the bronchial mucosa showed non-specific chronic inflammation.