Late recurrence of stage ⅠB gastric cancer with high microsatellite instability(MSI-high)is rare. Here, we report a case of MSI-high StageⅠB gastric cancer recurring more than 5 years after surgery. A 78-yaer-old man was admitted to our hospital for gastric cancer surgery. Laparoscopic distal gastrectomy was performed. Histologic examination revealed a T2(MP) N0M0, HER2-negative, StageⅠB gastric tubular adenocarcinoma. Postoperatively, the patient received chemotherapy with S-1 for 1 year. He developed liver and para-aortic lymph node metastases 5 years 1 month after surgery. Pathological genetic examination revealed a high microsatellite instability. He received pembrolizumab therapy for the recurrence. This case suggests that late recurrence occurs in patients with gastric cancer with high microsatellite instability.