A 42-year-old woman was referred to our hospital for the treatment of pyloric stenosis. Esophagogastroduodenoscopy (EGD) and computed tomography (CT) revealed the presence of type 4 advanced gastric cancer with bladder metastasis and peritoneal dissemination. Biopsy specimen examination revealed poorly differentiated adenocarcinoma with signet ring cell carcinoma. Thus, two cycles of chemotherapy with 5-fluorouracil, leucovorin, and oxaliplatin were administered. Subsequently, the gastric lesion and bladder metastasis reduced as detected using EGD and CT. Consequently, she achieved adequate oral intake. After changing the regimen to tegafur/gimeracil/oteracil and oxaliplatin, she was discharged. Currently, she continues to receive chemotherapy.