Nonoperative management (NOM) of hemodynamically stable patients has become standard; however, an important issue remains about the decision to undertake surgical exploration. We report a case of hepatic injury (IIIb type) in which 3D-CT cholangiography (3D-DIC-CT) was useful for deciding to change from NOM to laparotomy. A 30-year-old man had crushed his right back while mountain-biking downhill. He was found about 2 hours after his accident and then transferred to our hospital after initial fluid resuscitation. Radiological examinations showed multiple right rib fractures, hemo-pneumothorax, intraperitoneal hemorrhage, and type IIIb liver injury. Because his vital signs were stable, we chose NOM after inserting a chest tube. During hospitalization, aspartate aminotransferase and white blood cell count decreased, aggravation of intraperitoneal bleeding was not seen on an abdominal CT or focused assessment with sonography for trauma. However, 3D-DIC-CT showed leakage in posterior branch of the bile duct. Furthermore, the Bilirubin value in ascites was found to have increased. Thus laparotomy was carried out 3 days after admission. A posterior segmentectomy of the liver was performed. The post operative clinical course was uneventful. 3D-DIC-CT was demonstrated to have a role in changing for laparotomy in the NOM of hepatic injury.