Abstract: The treatment of gastric cancer in Japan is formulated according to the classification and the guidelines describe treatment methods.The last revision of Japanese Gastric Cancer Treatment Guidelines adopted the 7th edition of TNM stage classification, which was a major revision since the publication. This revision of the 15th edition of the classification is a combination of the revision of the 8th edition TNM classification and clinical experience. A stage revision and a clinical stage were newly established.In addition, the guidelines for the treatment of gastric cancer have also been revised at the same time, becoming the 5th edition, consistent with the new classification and its stage classification. Clinical trials on nationwide wellcontrolled gastric cancer surgery have come to be carried out in recent years, and these results are the source of evidence for the world.These results are also included in this revised guideline. Expansion surgery such as left thoracotomy and laparotomy for esophageal infiltrating gastric cancer and prophylactic para aortic lymph node dissection is denied from these clinical trials. In total gastrectomy for advanced gastric cancer that does not invade the greater curvature, splenectomy is unnecesary. Since gastrectomy followed by chemotherapy did not show any survival benefit compared with chemotherapy alone in advanced gastric cancer with a single noncurable factor and without bleeding or stenosis, gastrectomy cannot be justified for treatment of patients with these tumors. Laparoscopic pyloric lateral gastrectomy for early gastric cancer is fairly widespread and it is not an exaggeration to say that it is a standardized treatment. However, totally laparoscopic gastrectomy for advanced gastric cancer is currently awaiting results of randomized controlled trials.