The patient was an 81-year-old male. During treatment of a refractory subcutaneous abscess, he was diagnosed with an infection of an infrarenal aortic aneurysm caused by unknown bacteria. Antibiotic administration was initiated, but the infection persisted and there was no improvement of the aortic infection focus or aneurysm morphology. In order to control the infection and avoid rupture of the aortic aneurysm, excision of the infectious abdominal aortic aneurysm, omental plombage, and debridement of the surrounding infected tissue were performed. According to histopathological examination of the extracted sample, findings were consistent with an infection of the aortic aneurysm. Although administration of antibiotics continued, the infection continued to worsen during the postoperative course and an enlarged subcutaneous abscess and miliary tuberculosis were indicated by computed tomography. Therefore, an acid-fast bacteria culture test of the subcutaneous abscess, sputum, and urine and Tuberculous (Tb)-real time polymerase chain reaction (PCR) tests were carried out. According to Tb-PCR test of the subcutaneous abscess, mycobacterium tuberculosis was detected. In the re-evaluation of the extracted sample, granulomatous inflammation with spindle-shaped cell fenestration around the necrotic tissue and the appearance of epithelial cells and multinucleated giant cells were observed. Findings were consistent with a tubercular infection of the aortic aneurysm. Anti-tuberculosis treatment was initiated, and significant improvement of the inflammation and subcutaneous pus in the right chest were observed. On Day 39 after surgery, the patient was discharged from the hospital and walked home with no help. We experienced a successful case of tubercular infection of an infrarenal aortic aneurysm requiring surgery. Infection was controlled and rupture of the aortic aneurysm was avoided with surgical treatment and antituberculosis therapy. (Surgical treatment by excision of infectious abdominal aortic aneurysm, omental plombage, and debridement of the surrounding infected tissue, and antituberculosis therapy were carried out.)