Takayasu's arteritis is a chronic inflammatory disease that primarily affects large vessels, such as the aorta and its main branches. Pulmonary artery is often involved in Takayasu's arteritis, but only a few cases have been reported in which pulmonary artery involvement occurred as the initial clinical manifestation. We report one patient who was referred to our institution with the provisional diagnosis of chronic thromboembolic pulmonary hypertension and subsequently diagnosed with Takayasu's arteritis involving the pulmonary artery.