Budd-Chiari syndrome is characterized by hepatic venous outflow obstruction. We describe a patient with a huge caudate lobe of the liver due to Budd-Chiari syndrome. A 49-year-old woman was referred to Nippon Medical School Hospital to receive treatment for enlarged gastric varices. She had been followed up for idiopathic portal hypertension with deformity of the liver for 7 years and had undergone surgery for pharyngeal carcinoma 5 years earlier. Upper gastrointestinal endoscopy revealed solitary gastric varices without esophageal varices. Abdominal computed tomography revealed obstructions and scars of the right, middle, and left hepatic veins. The caudate lobe was enlarged, and the portal vein was displaced ventrally, without thrombus. The drainage vein of the caudate lobe, the short hepatic vein on the left side of the inferior vena cava, was dilated. The portal vein and drainage vein of segment 6 were visualized and showed no atrophy. Venography revealed no obstruction of the inferior vena cava. Budd-Chiari syndrome with solitary gastric varices was diagnosed on the basis of these findings. We performed balloon-occluded retrograde transvenous obliteration and partial splenic embolization to treat the gastric varices. The posttreatment course was uneventful, and the patient was discharged 8 days after embolization. The gastric varices shrank.