Objective: IgG4-related sclerosing cholecystitis is generally associated with IgG4-related sclerosing cholangitis and presents with diffuse, circumferential thickening of the gallbladder wall. We report a rare case of localized IgG4-related sclerosing cholecystitis without IgG4-related sclerosing cholangitis, which was difficult to differentiate from gallbladder cancer preoperatively.Patient: A 56-year-old man with suspected IgG4-related disease or gallbladder cancer was admitted to our ward. The serum IgG4 level was elevated at 721 mg/dL. Computed tomography (CT) demonstrated focal wall thickening of the gallbladder fundus. Drip infusion cholecystocholangiography with CT revealed no dilation, stenosis, or border irregularity of the bile duct.Results: For diagnostic and treatment purposes, cholecystectomy with wedge resection of the gallbladder bed was performed. The pathological diagnosis was IgG4-related sclerosing cholecystitis.Conclusion: It is difficult to differentiate IgG4-related sclerosing cholecystitis from gallbladder cancer in cases involving localized thickening of the gallbladder wall. In similar cases, surgical resection with cancer in mind might be performed based on present clinical knowledge.