Perforated gastric cancer typically requires life-saving emergency surgery. However, preoperative diagnosis is difficult, the rate of radical resection is low, and the prognosis remains poor. Perforated gastric cancer is generally treated with 1- or 2- stage gastrectomy, but radical resection is rarely performed after a conservative medical management and chemotherapy for perforated gastric cancer. A 65-year-old man visited another hospital with left upper abdominal pain. He was diagnosed with upper GI perforation, and conservative medical management was selected because peritonitis was limited. After close examination, a Type 3 tumor was found in the cardiac region of the stomach. As the advanced gastric cancer was unresectable, chemotherapy, comprising4 courses of SP plus T-mab, was subsequently administered. As the therapeutic effect was PR, we performed total gastrectomy. The pathological findings were tub2>tub1>por2: pT2N1CY0H0P0M0, pStageⅡ, and we achieved curative resection. Postoperatively, S-1 treatment was performed as an adjuvant chemotherapy. The patient remains alive, without recurrence, for 3 years and 6 months postoperatively.