Acute subdural hematoma (ASDH) is a neurosurgical emergency. Spontaneous resolution of acute subdural hematoma is extremely rare and the mechanisms are still unclear. However, several mechanisms of spontaneous resolution of acute subdural hematoma have been reported. We have witnessed a patient with a spontaneously resolved subdural hematoma within 14 hours after the initial diagnosis by cranial CT that had been performed just 1 hour after a traffic accident. To our knowledge, a rapid resolution like this has been reported for 36 cases previously. In this article, we report a patient with a rapidly spontaneous resolution of ASDH. We discussed resolution of ASDH mechanisms and also review the literature.