A 76-year-old man who had an abdominal aortic aneurysm underwent vascular replacement, and an acute spinal epidural hematoma developed postoperatively despite the absence of abnormal preoperative laboratory data other than hypertension. General anesthesia was induced using nitrous oxide, oxygen, and sevoflurane (GOS), and epidural anesthesia was also performed at the intervertebral space between Th10 and Th11. At 5 days after operation, an emergency operation was carried out to remove the epidural hematoma, which was noted at the Th5-Th9 vertebral level. The patient's clinical course was relatively favorable, and he was eventually able to walk with a stick. The cause of this acute hematoma remains unclear, but the following important factors might have been involved in its development: a transient bleeding tendency caused by intraoperative use of heparin as well as adverse effects to the epidural blood vessels due to an increased venous pressure following the surgical procedures. Our patient, fortunately, had no significant sequelae. However, when performing epidural anesthesia, it is necessary to keep in mind that epidural hematoma, though observed very rarely, may develop, particularly in patients with a tendency for bleeding.