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 complained of sputum lasting for several months. Chest computed tomography showed an air-containing cystic structure in the trachea. Fiberoptic bronchoscopy demonstrated ostium arising from the right posterolateral wall at the trachea. Reported herein is a case of eosinophilic bronchitis associated with tracheal diverticulum.