Congenital bronchial atresia is a relatively rare malformation that causes a segmental obstruction of the bronchus during the fetal period. The peripheral lung distal from the obstructed bronchus becomes hyperinflated because of the unidirectional flow through collateral check-valve entry. Positive pressure ventilation during general anesthesia may cause a rupture of the bulla, resulting in pneumothorax. An 8-year-old girl, who had to undergo oral surgery, was diagnosed as having congenital bronchial atresia and one-fifth of her lung was poorly ventilated. We planned to perform general anesthesia under spontaneous respiration using a laryngeal mask, which was well tolerated.