A 48-year-old man was admitted to our hospital because of an abnormal shadow on the chest rentogenogram detected by the regular health screening. A tumorous shadow about 10 mm in diameter existed in the right lower lobe on chest X-ray film. It was suggested that the tumor was receiving blood flow from the aortic system by IVDSA and dynamic CT, right bronchial angiogram demonstrated a dilatation and aneurysm formation associated with anastomosis of the pulmonary artery. Aneurysmectomy and right bronchial arterial ligation were performed, and no other complication was observed. Bronchial artery aneurysm is a rare disease, and 25 cases have been previously reported in the literature in Japan.