KEYNOTE-158 and 061 trials revealed the efficacy and safety of pembrolizumab(KEYTRUDA®)treatment in patients with recurrent high microsatellite instability(MSI-high)gastric cancer following gastrectomy. Here, we successfully treated an elderly case with recurrences following radical gastrectomy for advanced gastric cancer using pembrolizumab as a second- line chemotherapy. Even in elderly patients, pembrolizumab might contribute to effective and safe treatment in late-line chemotherapy for recurrent MSI-high gastric cancer.