A 54-year-old man underwent laparoscopic distal gastrectomy with D2 lymph node dissection and ante-colic Roux-en-Y reconstruction for gastric cancer. The histopathological diagnosis was pT2N3aM0, pStage ⅢA, HER2 negative. After 8 courses of S-1 plus oxaliplatin as adjuvant chemotherapy, he was diagnosed as peritoneal dissemination and treated with ramucirumab(RAM)plus paclitaxel(PTX). On the 12th day of course 10, he visited to our hospital with abdominal pain. CT showed free air and massive ascites. Emergent surgery was performed under the diagnosis of gastrointestinal perforation. A small intestinal perforation in front of the jejunal limb near gastric-jejunal anastomosis was identified and there was no peritoneal dissemination. We performed partial resection of remnant stomach and jejunal limb by linear stapler and reconstruction by end to side gastric-jejunal anastomosis. Because the gastric and intestinal wall were quite fragile and RAM impaired wound healing as adverse event, we feared about leakage, but he had no major postoperative complications and discharged on the 33th day after surgery. After 24 courses of nivolumab as third-line chemotherapy, the peritoneal dissemination disappeared. He has been alive without recurrence for about 1 year since then.