On the mandibular reconstruction after tumor resection, it is easy to achieve esthetic and functional results when mandibular defect is relative small, however, it is difficult to reconstruct adequately larger defected mandible. Recently, with progress of devices, distraction osteogenesis that is the method of tissue regeneration is used as mandibular reconstruction. A 19-year-old male patient presented complaining of right lower jaw swelling. Biopsy suspected a multiple-cystic ameloblastoma in mandible. Under the general anesthesia, a mandibulectomy was performed from the right side ramus to the left side incisor. A mandibular reconstruction plate was attached to the proximal and distal bone segments. 2 types of intraoral distraction devices were placed inside the plate. These devices had 25 mm and 60 mm distraction length. After 9 days of latency, trifocal bone transport was started by 0.5 mm 2 times activation per day. After consolidation for 23 weeks, reconstruction plate and distraction devices were removed. 2.5 m x 2.0 cm iliac bone and cancellous bone were placed in the docking site with platelet rich plasma. The mandibular defect (85 mm) was reconstructed adequately using intraoral distraction osteogenesis trifocal bone transport technique. Symmetric facial balance was achieved. Now there is no recurrence and dental implants were placed on new bone.