A 67-year-old man was admitted to our hospital because of a sudden onset of gait disturbance and behavioral abnormalities. On the admission, he had a moderate consciousness disturbance and right hemiparesis with left internal carotid artery occlusion. Eight days after the stroke, the patient further developed left hemiparesis in association with right internal carotid artery occlusion. Despite anticoagulation therapy and plasma volume loading, neurological symptoms deteriorated over a month, during which CT scan demonstrated a progressive expansion of infarct size. Laboratory tests revealed the presence of lupus anticoagulant. Antiphospholipid antibody syndrome may be associated with a progression of ischemic stroke.