Gastric cancer is the most common cancer and the fourth most common cause of cancer death in South Korea. Despite the large number of gastric cancer patients newly diagnosed and treated annually in South Korea, there has been no appropriate practice guideline for domestic medical situations. Although Korean guidelines for gastric cancer were published through interdisciplinary collaborations in 2004 and 2014, they were not widely used in South Korea. Therefore, we have produced the present clinical practice guideline to create guidelines that can provide the standard of gastric cancer treatment in accordance with the medical reality in South Korea