A 56-year-old female experienced sudden excruciating pain extending from the upper neck to the lower back. She had mild disturbance of consciousness, and a lumbar puncture revealed bloody cerebrospinal fluid. The positive neurological findings were meningitis, spastic paraparesis, hyperesthesia of the left L3 dermatome, bilateral Babinski, disappearance of anal reflex, and urinary retention. Computed tomography scans, myelography, and magnetic resonance images revealed diffuse subarachnoid hematoma and hematomyelia from Th12 to L3. Spinal angiography was tried twice before surgery but no origin of this diffuse hematoma could be found. Laminectomy was performed from Th12 to L1 and organized hematoma was found in the subarachnoid space. After the hematoma removal, non-pulsating tortuous vessels were observed on the surface of the spinal cord at the L1 level which ran into the intramedullary region. However, there was no further abnormality to define spinal arteriovenous malformation or fistula within the limits of exposure. The postoperative course was uneventful and about 2 months later she was able to walk by herself.