Atrophic gastritis is caused by Helicobacter pylori infection, and is involved in gastric cancer. In this study, we investigated the association with total IgG and IgG subclass antibodies using several strains isolated from Japanese in H. pylori positive and negative individuals, and gastric atrophy using measuring pepsinogen I and II levels. We found that total IgG antibody measurement using typical Japanese genotype as an antigen was available for diagnosis of H. pylori infection, whereas IgG1 and IgG2 antibodies were not for diagnosis. Furthermore, the IgG1/G2 ratio was elevated in a patient with gastric cancer. The accuracy of serodiagnosis of H. pylori infection may increase when the optimal antigens are used, and measurement IgG subclass may provide additional prediction of gastric cancer.