Spontaneous bilateral cerebellar infarction in the territory of the superior cerebellar arteries is extremely rare. Occasionally there have been reports of bilateral cerebellar infarction due to vertebrobasilar atherosclerotic occlusion or stenosis, whereas no report of bilateral cerebellar infarction due to complicated hemodynamic changes. In this report, we present a patient with bilateral cerebral infarctions related to stenoses of bilateral internal carotid arteries, in whom vertebrobasilar system was supplied by multiple collaterals from both posterior communicating arteries and right external carotid artery. We performed stent-angioplasty of bilateral internal cerebral arterial stenosis, and then acute infarction developed on bilateral superior cerebellar artery territories. The authors assumed that the infarction occurred due to hemodynamic change between internal carotid artery and external carotid artery after stent-angioplasty for stenosis of right internal carotid artery.