A 3-year-old girl was admitted to hospital with complaints of severe upper abdominal pain and vomiting. On admission, a board-like rigidity in the right hypochondrium was noted, along with a high white blood cell count and a high C-reactive protein value. Abdominal ultrasonography (US) revealed a left-sided enlarged gallbladder with a thickened wall, without gallstones. Contrast-enhanced computed tomography (CT) demonstrated an enlarged gallbladder without enhancement effects and a cystic duct located on the right side of the gallbladder. The patient underwent an emergency operation following a diagnosis of torsion of the gallbladder. The gallbladder appeared gangrenous, and 180 degrees clockwise torsion was found at the neck of the gallbladder. The gallbladder was straightened and then removed without difficulty because there was only slight inflammation around Calot's triangle and the gallbladder was not fixed to the liver. Histopathological examination revealed an acute bleeding infarction of the gallbladder. The patient was discharged on the ninth day after surgery, without any complications. The present case suggested that abdominal US and contrast-enhanced CT examinations are helpful in making a correct diagnosis of torsion of the gallbladder even in an infant; in the event of this diagnosis, prompt cholecystectomy is necessary.