We report a case of cerebral hemorrhagic infarction after radiation for pituitary adenoma. A 55-year-old woman was hospitalized to check for aldosteronism, post-operative pituitary function, and recurrence of thyroid cancer. She had short-term memory disturbance beginning two months prior to admission. Brain MRI showed a T1 and T2 high intensity lesion of her left anterolateral thalamus. Brain MRA revealed a narrowing in her left middle cerebral artery. The abnormal brain lesion was diagnosed as cerebral hemorrhagic infarction. She had received radiation therapy for pituitary adenoma 20 years earlier. It was considered that her cerebral hemorrhagic infarction was caused by radiation therapy.