Althogh peripheral pulmonary aneurysm is a rare entity, the majority of cases become fatal if left untreated, due to sudden rupture and exsanguination. This emphasizes the need for treatment whenever a diagnosis made. A 81-year-old woman was found to have a coin lesion in the left middle field. Enhanced computed tomography (CT) showed strong staining and pulmonary angiography revealed a saccular dilation of the left A3b branch of the pulmonary artery. Successful embolization of the branch of the pulmonary artery was performed.