Postoperative bleeding is one of the most frequent complications of tooth extraction. Although most are controllable using local treatment, arterial bleeding is sometimes uncontrollable. In this paper, we report uncontrollable postoperative bleeding caused by a pseudoaneurysm, which may have developed after tooth extraction of the right upper third molar. It was treated by transcatheter arterial embolization. The patient was a 45-year-old woman. She had undergone extraction of the right upper third molar at a dental clinic. She was referred to our hospital six days after the extraction, due to intermittent oral bleeding, nasal bleeding and cheek swelling. Contrast-enhanced CT and angiography showed a pseudoaneurysm nearby the wound after extraction. The pseudoaneurysm was treated using coil embolization with interventional radiology.