A durable response after the discontinuation of immune checkpoint-inhibitor therapy has previously been reported in several cancers. We herein describe a patient with gastric cancer who maintained a durable response after the discontinuation of nivolumab. A 65-year-old man was treated with nivolumab as a sixth-line therapy for recurrent gastric cancer. After four cycles of nivolumab therapy, he showed a partial response. But the treatment was discontinued when two immune-related adverse events occurred after six cycles. Disease regression was sustained for approximately 2 years, without the re-administration of nivolumab. The characteristics leading to such responses are unclear, and further studies are warranted in this regard.