Mandibular fracture is one of the complications of mandibular impacted wisdom tooth extraction. However, it is very rare, occurring with a frequency of 0.0033 to 0.0049%. We report a case of mandibular fracture after extraction of an impacted mandibular wisdom tooth. The patient was a 56-year-old male. Under local anesthesia, an impacted right mandibular wisdom tooth was extracted at our department. The day after surgery, dysesthesia occurred in the area innervated by the inferior alveolar nerve. He noticed an unusual sound in his right mandible when he ate a snack on the 5th day after wisdom tooth extraction, and had pain and mild swelling in the affected area on the 11th day. On the 33rd day, trismus, malocclusion, and drainage from the extraction socket were observed, so a panoramic radiograph was taken, which revealed a fracture of the mandible. On the 54th day, open reduction with internal fixation of the mandibular fracture was performed under general anesthesia. At present, 5 months have passed since the open reduction surgery; the malocclusion and paresthesia have improved and a good course has been obtained.