Purpose: Although outcomes of surgical treatment for advanced gallbladder carcinoma remain unsatisfactory, radical resection may provide a favorable prognosis for patients with tumors limited to shallow subserosal invasion (Subjects and Methods: A retrospective analysis of ultrasound-pathologic correlation was conducted in five patients with shallow pT2 gallbladder carcinoma of the papillary invasive type. Results and Discussion: The outermost hyperechoic layer comprises deep adipose tissue of the subserosa plus serosa. A polypoid gallbladder tumor with a hypoechoic area in its deeper part represents a papillary adenocarcinoma invading the subserosa accompanied by abundant fibrosis and lymphocytic infiltration. All cases in the present study had the deep hypoechoic area. Three of the five cases showed thickening of the outermost hyperechoic layer, and two cases showed no change in the layer. There have been no reports highlighting thickening of the outermost hyperechoic layer. Given the vertical extension of carcinoma invasion, the outermost hyperechoic layer may be pulled up and thickened at first and then thinned later as the deep hypoechoic area enlarges. Conclusion: Ultrasound images of shallow pT2 gallbladder carcinoma of the papillary invasive type show thickening or thinning of the outermost hyperechoic layer. The former demonstrates pulling up the top of the layer at first and then thinning later as carcinoma invasion progresses showing enlargement of the deep hypoechoic area. The latter shows thinning of the layer from beginning to end.