We report a rare case of pulmonary artery sarcoma mimicking pulmonary artery thromboembolism in a 57-year-old man who suffered with 2-month dyspnea and exacerbated for 1 week. He was transferred from private clinic and he was diagnosed as acute pulmonary artery thromboembolism on the basis of chest CT. Chest CT, pulmonary artery angiogram, and perfusion scan were examined. We performed surgical excision with aid of CPB. The final pathologic report was that the mass was a pulmonary artery sarcoma. We experienced one case of pulmonary artery sarcoma and reported it with reference.