Takayasu's arteritis has often been difficult to diagnose because of a lack of typical symptoms and other specific makers. We report here a case of Takayasu's arteritis in a 73-year-old man who was considered to exhibit isolated pulmonary artery involvement. Pulmonary hypertension and right heart failure and severe stenosis in the main trunk and left pulmonary artery were observed. There was nothing remarkable in his routine blood-sample tests other than increased CRP and ESR. There were neither infectious nor collagen diseases. Anti-cardiolipin antibody, Antiphospholipid Syndrome, PR3-ANCA and MPO-ANCA were negative. We diagnosed the patient as having Takayasu's arteritis based on chronic inflammation and the morphologic features of pulmonary artery lesion. However, other large vessels and the aorta were not involved. Treatment was started with glucocorticoids. The symptoms gradually improved, and pulmonary artery pressure estimated by echocardiography decreased along with inflammatiory markers. There were no remarkable changes in the stenotic lesions in the pulmonary artery but the flow limit in the left pulmonary artery was improved.