We report renal artery injury by a guidewire during coil embolization of a cerebral artery aneurysm, which was successfully treated by transarterial embolization using n-butyl-2-cianoacrylate (NBCA). Case Presentation: A 65-year-old woman underwent coil embolization for an unruptured cerebral aneurysm, resulting in its complete occlusion. However, her blood pressure decreased during embolization and postoperative abdominal computed tomography (CT) revealed a retroperitoneal hematoma. Intraoperative video revealed that the 0.035-inch guidewire had passed deeply into the right renal artery when the guiding sheath was navigated into the abdominal aorta, suggesting renal artery perforation. Transarterial embolization using NBCA was performed immediately, which resulted in hemostasis. Conclusion: Although renal artery perforation with a guidewire is a rare complication, it can have severe consequences. Early diagnosis with prompt and definitive hemostasis is important.