A 65-year-old female who presented with back pain was diagnosed to have the presence of biliary sludge in the gallbladder. Computed tomography showed that the round ligament connected to the left portal umbilical portion was in the normal anatomical position. However, the gallbladder was located to the left of the middle hepatic vein and the round ligament, attached to the left lateral segment of the liver. The right posterior portal vein diverged alone from the main portal vein, and there was a long stem from the right anterior and left portal veins. Laparoscopic cholecystectomy confirmed the abnormal location of the gallbladder. Most reported cases of left-sided gallbladder are caused by a right-sided round ligament, which is called a "false" left-sided gallbladder. A case of left-sided gallbladder with a normal left-sided round ligament, which is designated as a case of "true" left-sided gallbladder, is extremely rare.