This case presents a 34-year-old man who had a huge parasagittal meningioma. Initial treatment consisted of preoperative external carotid artery embolization and partial tumor resection. During the resection, we found that the tumor invaded the adjacent calvarium, and due to massive hemorrhage, total removal of the tumor was impossible. The patient was treated with intraoperative radiation therapy (IORT) (25 Gy via 16 MeV) as an adjunctive therapy. Eight months after IORT, we were able to remove the tumor completely without surgical difficulties. IORT can be considered an useful adjunctive therapy for the superficially located, huge, and highly vascular meningioma.