We present a rare case of a 44-year-old man with acquired pulmonary stenosis caused by a calcified pericardial ring. Chest computer tomography and cardiac angiography showed external compression of the main pulmonary artery by a calcified pericardial ring. A calcified pericardial ring was removed and the pulmonary artery angioplasty was performed for the stenotic pulmonary artery. The patient's condition improved dramatically thereafter.