We report a case of Swyer-James syndrome with pneumothorax. A 20 year-old man was admitted to our hospital with dyspnea. Right pneumothorax was diagnosed by chest X-ray. He had a history of current pneumonia in childhood. After improvement of the pneumothorax, chest X-ray revealed hyperlucency of the right upper lung. Chest-CT revealed a low attenuation area and a cystic space in the right upper lobe. Xenon-133 clearance was delayed in ventilation scintigraphy. Bronchography showed cylindrical bronchiectasis in the proximal bronchi and poor filling of the peripheral bronchi in the right upper lobe. Pulmonary angiography showed a small right upper pulmonary artery. Swyer-James syndrome was diagnosed. The pneumothorax was probably caused by weakness of the cystic spaces.