There are many reports that obstructive sleep apnea syndrome (OSAS) is a risk factor for ischemic stroke of arterial origin, however, the relationship between OSAS and cerebral venous thrombosis (CVT) remains unknown. We report the case of a 44-year-old man who had episodic headaches, unconsciousness attacks and seizures. Cerebral angiography showed CVT. He was obese and had severe OSAS. Noninvasive continuous positive airway pressure (CPAP) therapy prevented the recurrence of CVT as well as of headache. OSAS may be one of the multiple risk factors of CVT as well as arterial ischemic stroke.