After X-ray examinations of a case complaining of upper abdominal pain it was suspected of twin gallbladder, and subsequently it was confirmed by peritoneoscopy. This paper described about this unusual case. It was demonstrated that this case had a twin gallbladder one lobe in front of another each of which measured about 3cm of diamater. This corresponds to the bilobed gallbladder reported by S. Sherlock. The anterior lobe was hardly functioning and hence the bladder function was performed by the posterior lobe. This point was verified by roentgenographs of the gallbladder as well as by peritoneoscopy.