Intraoperative MRI (iMR) and neuronavigation have substantially changed the principles of surgery for brain tumors. iMR provides updated information on anatomical data and unanticipated brain events, thereby allowing safer and more accurate surgery. We herein report a case of unanticipated intracranial hemorrhage in an iMR imaging suite. The patient was a 53-year-old man with a chief complaint of generalized convulsion. MRI showed a lesion in the right temporal lobe about 6.0 cm in diameter. The tumor was resected using an iMR system and neuronavigation. The first iMR images showed a residual tumor in the medial temporal lobe. No brain events were detected at this time. We obtained updated navigation data and performed additional resection. After completion of the planned tumor resection, additional iMR images were taken. The second iMR images confirmed that the tumor had been completely removed, but they also revealed a contra-lateral subdural hemorrhage. After expedited closure of the original incision, left unilateral craniotomy was performed and the hematoma was evacuated. Fortunately, the patient had no new neurological deficits. The use of iMR imaging allowed the complete removal of the tumor and facilitated prompt and effective identification of an unanticipated life-threatening complication.