Surgical site infection (SSI) is prominent among the total incidence of healthcare-associated infections, and is a major contributing factor in the trend of increasing medical costs. There have been numerous efforts to analyze the conditions and causes of SSI for the purpose of prevention. In this study of SSI development after gastric surgery, we evaluated the prevalence of specific pathogens and compared the clinical characteristics observed between gram-positive (GPB) and gram-negative bacteria (GNB).