We report on a 45-year-old woman with intimal sarcoma of the pulmonary artery. She presented with a chief complaint of shortness of breath. Computed tomography (CT) of the chest showed an intraluminal hypoattenuated area extending from the main pulmonary artery into the right main pulmonary artery and bilateral lobar pulmonary arteries. She underwent resection of the lobulated mass from the pulmonary artery. The tumor was diagnosed as an intimal sarcoma. Although she received chemotherapy with amrubicin and carboplatin when the tumor recurred, the tumor enlarged. After radiotherapy was performed, CT of the chest showed shrinkage of the tumor and the regression of consolidation and ground-glass opacity. Radiotherapy and chemotherapy are treatment option for patients with pulmonary artery sarcoma.