We report an extremely rare case of traumatic cervical spinal subdural hematoma not related to intracranial injury. There has been no report on traumatic cervical spinal subdrual hematoma not related to intracranial injury. A 27-year-old female patient was admitted to our emergency room due to severe neck pain and right arm motor weakness after car collision. On admission, she presented with complete monoplegia and hypoesthesia of right arm. Magnetic resonance imaging (MRI) revealed subdural hematoma compressing spinal cord. Lumbar cerebrospinal fluid (CSF) analysis revealed 210,000 red blood cells/$mm^3$. She was managed conservatively by administrations of steroid pulse therapy and CSF drainage. Her muscle power of right arm improved to a Grade III 16 days after admission. Follow-up MRI taken 16th days after admission revealed almost complete resolution of the hematoma. Here, the authors report a traumatic cervical spinal SDH not associated with intracranial injury.