We report the surgical treatment of a rare case of true aortic aneurysm in a right-sided aortic arch. A 49-year-old female patient with obstructive respiratory problems demonstrated a true aneurysm with a diameter of 58 mm located at the right-sided aortic arch between the right carotid artery and right subclavian artery. Surgery was successfully performed by replacing the arch including the aneurysm with a prosthetic graft. The positions of true aneurysms in the right-sided aortic arch can be divided into two subtypes: first, the transverse arch between the right carotid artery and right subclavian artery, and second, the base of the subclavian artery, the Kommerell's diverticulum. The region is informative for consideration of the surgical approach toward aneurysms of this entity.