A 78-year-old female patient with stomach cancer (with hepatic metastasis and peritoneal dissemination) had received eight courses of an S-1 and oxaliplatin regimen as palliative chemotherapy. Computed tomography revealed liver deformities and incidental gastric varices. Esophagogastroduodenoscopy confirmed the findings of gastric varices in the cardia and fornix. It was suspected that oxaliplatin-based chemotherapy had induced non-variceal portal hypertension in the patient-similar to that which is seen in patients with colon cancer who are treated with oxaliplatin-based chemotherapy. We had chosen balloon-occluded retrograde transvenous obliteration (BRTO) for the preventive treatment of gastric varices because the patient had a gastro-renal shunt, which enabled access to the gastric varices via the vena cava. Our patient had undergone BRTO, which resulted in the endoscopic disappearance of gastric varices. Currently, the patient is continuing chemotherapy without bleeding from gastric varices. Our case suggests that patients with gastric cancer treated with oxaliplatin-based chemotherapy require careful follow-up for portal hypertension.