Traumatic spinal subdural hematoma is a rare entity. Hemorrhage of intracranial arachonoid cyst is also uncommon. One 20 year-old man suffered from subacute intraspinal subdural hematoma in the sacral level after minor sports injury. He received spinal surgery for decompression and the symptoms recovered well after operation. Unfortunately, he suffered from sudden onset of aphasia one week later. Intracystic hemorrhage of pre-existing arachnoid cyst with adjacent subdural hematoma was found on CT and MRI of brain. The relation between these two events was discussed.