A 69-year-old man was administered S-1/oxaliplatin/trastuzumab as induction chemotherapy for advanced gastric cancer (cT4b[liver, pancreas], N2M1(H1P0CYX), cStage IV). After 4 courses, because contrast-enhanced computed tomography showed remarkable reduction of the tumor, distal gastrectomy, partial hepatectomy, and radiofrequency ablation for the liver metastasis were performed. The patient was histopathologically diagnosed with gastric neuroendocrine carcinoma(NEC). S- 1/oxaliplatin/trastuzumab was continued after surgery; however, recurrence in the remnant liver was observed after 4 cours- es. For recurrence, cisplatin/irinotecan as first-line and paclitaxel/ramucirumab as second-line treatment were administered, but progression of liver metastasis and ascites due to peritoneal dissemination were observed. As third-line treatment, nivolumab was initiated. Ascites decreased after 3 courses, but after 2 more courses, progression of ascites, liver recurrence, and multiple metastasis in the lumbar vertebra were observed.