A 78-year-old man was diagnosed with a liver tumor on follow-up CT after thoracic aortic aneurysm surgery. Esophagogastroduodenoscopy revealed a type 2 tumor in the gastric antrum, a biopsy showed poorly differentiated adenocarcinoma, and CT revealed multiple liver metastases, resulting in a diagnosis of clinical Stage ⅣB(cT4aN0M1[HEP]). S-1/oxaliplatin (SOX)chemotherapy was started. However, after 9 courses of chemotherapy, the primary tumor continued to increase in size. Ramucirumab/paclitaxel(RAM/PTX)was started; after 3 courses, CT revealed shrinkage of the primary tumor and disappearance of multiple liver metastases. PET-CT showed no abnormal FDG accumulation in the stomach, surrounding lymph nodes, and liver. Therefore, the patient was considered to have a PR in efficacy, and a decision to perform conversion surgery was made based on the assumption that curative resection was possible. The patient underwent laparoscopic distal gastrectomy D2 lymph node dissection and Billroth Ⅰ reconstruction. The pathological result was M, Ant, type 2, por, ypT2N0M0, ypStage ⅠB, while the histological effect of the chemotherapy was Grade 0. The patient was treated with paclitaxel as adjuvant chemotherapy, which was discontinued 1 year after surgery owing to no recurrence. No recurrence has been noted during 2 years of follow-up.