We report a patient who underwent an operation for an infectious abdominal aortic aneurysm 10 months after intravesical bacillus Calmette-Guerin therapy. A 68-year-old man had previous gastrectomy for early gastric cancer and intravesical BCG therapy for early stage urinary bladder cancer. His follow up CT scan revealed an abdominal aorta pseudoaneurysm. We performed aneurysmectomy, omentopexy and bilateral axillo-femoral bypass. The culture of an abscess in the aneurysm identified Mycobacterium bovis. The patients improved clinically with antituberculosis agents after operation. Intravesical bacillus Calmette-Guerin therapy is effective in the treatment of early stage urinary bladder cancer. Although this treatment is generally considered safe, serious complications including vascular complications have been reported.