Meckel's diverticulum (MD) is a common congenital anomaly of the gastrointestinal tract, the majority of cases of which are clinically silent. Patients with asymptomatic MD can unexpectedly develop acute abdominal pain. Making a diagnosis of MD is often difficult due to the lack of specific symptoms caused by this condition. Diagnostic laparotomy can be useful for making an accurate and prompt diagnosis of complicated MD. We herein describe a pediatric case of torsion of a MD in whom we performed laparoscopic-assisted emergency surgery. The patient was an 11-year-old male who developed sudden severe right lower abdominal pain. Clinical and laboratory findings were suggestive of appendicitis, however computed tomography scans showed a large cystic mass in the pelvis. Exploratory laparoscopy led to a diagnosis of torsion of a MD, and wedge resection of the gangrenous MD was performed through an umbilical port incision. The patient's postoperative course was uneventful. We conclude that diagnostic laparoscopy followed by laparoscopy-assisted Meckel's diverticulectomy via an umbilical incision is useful in the treatment of acute abdomen caused by MD.