Double gallbladder is a rare congenital malformation and generally considered a duplication of 1 primordium. We encountered an extremely rare case of double gallbladder of the duodenal type that was considered a duplication of 2 primordia. We were able to diagnose the anomaly preoperatively by endoscopic retrograde cholangiopancreatography and spiral computed tomography after intravenous infusion cholangiography, and laparoscopic removal was successfully performed. To our knowledge, this is the first reported case of double gallbladder of the duodenal type that was diagnosed preoperatively and treated successfully by laparoscopic removal.