We reported a 31 year-old man with repeated episodes of migraine at a frequency of about once a week on and after January, 2000. In January 2001, scintillating scotoma and pulsating headache appeared followed by left hemianopsia. His platelet count decreased to 80,000/microliter and high intensity areas were observed in the right occipital lobe and hippocampal gyrus on the FLAIR image of brain MRI. Subsequently performed brain MRA and vertebral angiography revealed segmental stenosis and obstruction in the right posterior cerebral artery. Under the diagnosis of migrainous infarction, sodium ozagrel and lomerizine hydrochloride were administered. Idiopathic thrombocytopenic purpura was additionally diagnosed based on the decreased platelet count which was then treated with predonisolone. After these treatment, his migraine attack disappeared. In this patient, platelet destruction due to idiopathic thrombocytopinic purpura and subsequent release of serotonin seemed to have involved in the occurrence of migrainous infarction.