We reported a 77-year-old woman with atrial fibrillation. She was admitted to our hospital because of bradycardia and disturbance of consciousness. She regained consciousness soon after the admission, however on the 3rd day of admission, she abruptly fell into a coma. Neurological examination revealed decerebrate rigidity, conjugate eye deviation to the right, and bilateral Babinski signs, but remaining oculocephalic reflex in both vertical and horizontal directions. Diffusion-weighed MR image of the brain on the same day demonstrated extensive hyperintense lesions in the bilateral hemispheres, sparing the brainstem. On the duplex carotid ultrasonography just after the MR study, oscillating intraluminal thrombi occluded the right common carotid and the left internal carotid artery. We diagnosed the patient as having bilateral carotid occlusions by cardioembolic mechanism.