A 70-year-old man with epigastralgia who initially visited a local hospital was referred to us for further examination. Gastrointestinal endoscopy exhibited a type 3 tumor of the stomach from the body to the antrum(adenocarcinoma, por1). Contrast-enhanced CT revealed thickness in the wall of the gastric body with bulky lymph nodes and ascites. Staging laparoscopy showed that the patient was diagnosed with sStage Ⅳ gastric cancer with positive peritoneal cytology. Therefore, SOX therapy was administered. Subsequently, total gastrectomy with D2 lymph node dissection was performed, since the primary tumor and lymph nodes were significantly reduced. Histopathologically, the residual lesion was only observed in the mucosal layer without lymph node metastases. We herein report a case of Stage Ⅳ gastric cancer, which was successfully treated by conversion surgery after SOX therapy.