Multi-vessel cervical arterial injury after blunt trauma is rare, and its pathophysiology is unclear. Although blunt cerebrovascular injury is a common cause of cerebral ischemia, its management is still controversial. We describe a 23-year-old man in previously good health who developed three-vessel cervical arterial dissections due to blunt trauma. He was admitted to our emergency and critical care center after a motor vehicle crash. Computed tomography showed a thin, acute subdural hematoma in the right hemisphere and fractures of the odontoid process (Anderson type III), pelvis, and extremities. He was treated conservatively, and about 1 month later, he developed bleariness. Computed tomography angiography showed bilateral internal carotid and left vertebral artery dissection. Aspirin therapy was started immediately, and then clopidogrel was added to the regimen. Two weeks later, magnetic resonance angiography (MRA) showed improved blood flow of the vessels. Only aspirin therapy was continued. About 3 months after discharge, MRA demonstrated further improvement of the blood flow of both internal carotid arteries, but the dissection flap on the right side remained. Therefore, we extended the duration of antiplatelet therapy. On the basis of our experience with this case, we think that antithrombotic therapy is crucial for the management of multi-vessel cervical arterial injury, and agents should be used properly according to the injury grade and phase; however, further study is needed to confirm this recommendation.