Tracheal diverticulum is relatively rare. It results from congenital or acquired weakness of the tracheal wall. Most cases are asymptomatic, but when symptoms are present they are usually nonspecific. A 54-year-old man had complained of sputum for several months. Chest computed tomography showed an air-containing cystic structure of the trachea. Fiberoptic bronchoscopy demonstrated ostium arising from the right posterolateral wall at trachea. We report a case of eosinophilc bronchitis associated with tracheal diverticulum.