A 65-year-old man was referred for a gallbladder elevated lesion. Abdominal US showed a hypoechoic tumor with wide base at the gallbladder body. The maximum velocity of the gallbladder wall blood flow was 20 cm/s. The outermost hyperechoic layer was irregular, but not disrupted on EUS images. We diagnosed the lesion as gallbladder carcinoma with the depth of subserosa. Cholecystectomy was performed and the tumor was diagnosed as tubular adenoma of the gallbladder. The p53 immumostaining was negative. A gallbladder adenoma with wide base is rare, here we report this case with the several considerations.