Patients who have ever failed in the eradication of H. pylori by the triple therapy containing clarithromycin are randomly assigned to the dual therapy with vonoprazan 20 mg bid and amoxicillin 500 mg tid for 1 week or the triple therapy with vonoprazan 20 mg bid, amoxicillin 750 mg bid and metronidazole 250 mg bid for 1 week.