To clarify that serum antibody of Helicobacter pylori (H. pylori) and serum pepsinogen I/II ratio are useful or not as a marker of the judgment after eradication therapy, we followed up 84 cases who received eradication therapy comparing with culture and histology (Carnoy's fixation and immunostaining using anti-H. pylori antibody, MIA method). Successful eradication was recognized in 45 of 84 cases (successful group), and remaining 39 cases were unsuccessful (unsuccessful group). Titers of serum H. pylori antibody went down gradually in the successful group, on the other hand, they did not go down constantly and often re-went up in the unsuccessful group. The difference of the various rate of titers in the both groups became clear statistically since 6 months after eradication therapy (p < 0.05). Supposing that cut-off rate of titer was 60% of pre-eradicated titer, sensitivity, specificity, and accuracy were 86.2%, 77.7%, and 84.2%, respectively, at 6 months after eradication therapy. Serum pepsinogen I/II ratio increased regardless of successful or unsuccessful eradication, but the various rate of serum pepsinogen I/II ratio was different in both groups at 1 month and 3 months after eradication therapy (p < 0.05). Serum antibody of H. pylori and serum pepsinogen I/II ratio could be a marker of the judgment after eradication therapy, especially the various rate of serum antibody of H. pylori is useful for the monitor of H. pylori infection in the long term.