We present a case of gastric cancer with portal vein tumor thrombosis. A 77-year-old man visited our hospital because of epigastric pain. Esophagogastroduodenoscopy and computed tomography (CT) revealed advanced gastric cancer. Total gastrectomy was performed. During surgery, peritoneal dissemination was found. Histopathological diagnosis was Stage IV gastric cancer (por2, T4aN3M1) with massive vascular invasion. He was treated with a chemotherapy regimen of S-1 plus docetaxel for approximately 2 years after which the regimen was changed to S-1 monotherapy. Six months later, CT revealed portal vein tumor thrombosis (PVTT) without progression of peritoneal dissemination. The metastatic route of PVTT was believed to be hematogenous because neither liver nor lymph node metastasis was detected. The regimen was shifted to CPT- 11 plus cisplatin therapy since the effects of the treatment was evaluated as progressive. The patient was alive with stable disease after 5 courses of chemotherapy. PVTT should be taken into consideration as a possible type of recurrence when the tumor is associated with massive vascular invasion, although gastric cancer with PVTT is rare.