Aspirin has been widely used as an anti-platelet drug for the primary or secondary prevention of cardiovascular events, including ischemic heart disease and stroke. In 2016, the U.S. Preventive Services Task Force recommended initiating low-dose aspirin use for the primary prevention of cardiovascular diseases and colorectal cancer in adult aged 50 to 59 years who have a 10% or greater 10-year cardiovascular disease risk, are not at increased risk of bleeding, have a life expectancy of at least 10 years, and are willing to take low-dose aspirin daily for at least 10 years. In addition, a meta-analysis reported that long-term aspirin use was associated with reduced the risk of gastrointestinal cancers including colorectal cancer, esophageal cancer, and gastric cancer.However, most studies that reported the cancer prevention effect of long-term aspirin use were conducted as the secondary analysis or subgroup analysis of primary studies investigating the aspirin use for cardiovascular disease prevention. Thus, there is a limitation that appropriate sample sizes and follow-up periods for the cancer prevention effect of aspirin were not considered. In 2018, we reported that H. pylori treatment reduced the development of metachronous gastric cancer after endoscopic resection in early gastric cancer patients. However, metachronous gastric cancer could develop after successful H. pylori eradication with an annual incidence of 1%-3%. Therefore, we designed a multi-center, double-blind, randomized, placebo-controlled trial to evaluate whether long-term low-dose (100 mg) aspirin uses prevents gastric cancer in early gastric cancer patients without H. pylori infection.