Mycotic aneurysms located on aortic arch are rare and have extremely high mortality. The presented case is a 75-year-old man with a thoracic aortal mycotic aneurysm successfully treated with surgical intervention. To prevent recurrent infection and postoperative pulmonary complications, we performed single-stage surgery including extensive debridement, graft replacement using rifampicin soaked prosthetic graft and omental wrapping. Although mycotic aneurysm with inflammation tissue usually interferes with surgical manipulation because of severe adhesion to the lung, semi-clamshell approach helped us perform all these procedures. The patient rapidly recovered from the surgery, and has shown no recurrence after 35 months follow-up.