A 67-year-old woman with pneumonia and diabetes mellitus was admitted with the complaints of abdominal and back pain. Sputum culture was positive for Klebsiella pneumoniae. Computed tomographic scanning (CT) of the abdomen and spinal radiograph of the lumber column revealed a paraventebral space-occupying lesion, abdominal aortic aneurysm and destructive change of L3 and L4. Pseudoaneurysm of the abdominal aorta associated with infectious spondylitis with paravertebral abscess was suspected and confirmed by aortography. Klebsiella pneumoniae was cultured from the abscess. The patient's condition improved rapidly after drainage of the abscess and administration of LMOX and gentamicin. Infectious pseudoaneurysm of the abdominal aorta associated with infectious spondylitis has rarely been reported. These two in combination due to Klebsiella pneumoniae has not been reported to our knowledge. The pathologic changes were found easily by CT scan. When infectious aneurysm or infectious spondylitis is diagnosed alone, possible combination of these diseases should be kept in mind.