Antiphospholipid antibodies are a major risk factor of juvenile cerebral infarction; in addition, they can cause major arterial stenosis or occlusion. We report a case of a 32-year-old man who had been diagnosed with systemic lupus erythematosus at the age of 20 years, and was admitted to Shin-Oyama City Hospital, Tochigi, Japan, because of left arm weakness. Cerebral infarction and occlusion of the right internal carotid artery were found. Tests were positive for phosphatidylserinedependent antiprothrombin antibody, which can be useful for the diagnosis of antiphospholipid syndrome. Phosphatidylserine-dependent antiprothrombin antibody might have the potential to cause thrombosis and vasculitis-like occlusion.