A 74-year-old woman was admitted to our hospital with a diagnosis of a pseudoaneurysm 5 months after graft replacement of the ascending aorta, and underwent re-replacement employing left ventricle venting through a left anterior thoracotomy. Culture of the thrombi in the pseudoaneurysm revealed Psuedomonas infection. On the 11th postoerative day, a single-stage procedure of irrigation, debridment, and immediate closure with omental transposition was performed. Although the chest CT scan 1 month after the omental transposition revealed a residual abcess, it was completely obliterated after 2 months without further operation.