We experienced a surgical case with a large amount of hemorrhaging from an epidural puncture aperture immediately after surgery. The clotting studies, which were screened five days prior to surgery, were within normal limits. In the postoperative clotting studies, prothrombin time (PT) and hepaplastin test (HPT) demonstrated an unexpected coagulopathy, but activated partial thromplastin time (APTT) was still normal. These findings suggest that F VII, which is a vitamin K-dependent coagulation factor, should be decreased. So we suspected that this coagulopathy was caused by vitamin K deficiency. Preoperative oral limitation, insufficient absorption caused by ileus and treatment with cephem antibiotics had led to this deficiency. Vitamin K and fresh frozen plasma were intravenously administered just after these findings, and bleeding tendency was then improved; this patient now has no neurological impairment. We should pay attention when we administer cephem antibiotics containing N-methyl-thiotetrazole to a patient with long time fasting.