The purpose of this study is to examine the characteristics of principal leadership that influence the formation of a positive school culture. In this study, the formation of psychological safety, a theory that explains the belief of organization members will not be disadvantaged even if they freely participate in discussion, was assumed as a positive school culture. The characteristics of school and those of principal leadership were identified through in-depth interviews with selected teachers of elementary school where psychological safety has already been established. Based on the analysis of this study, principal leadership, which can be summarized as trustworthy leadership , supportive leadership , shared leadership , leadership without authority , and respectful leadership , played the most important role in building psychological safety. Analysis also revealed that cultural, environmental, and institutional factors, as well as principal leadership, affected the formation of psychological safety. Specifically, factors such as teacher community, decision making process, school size, Innovation school, and the Internal Open Recruitment System of Principals (IORSP) interacted in a complex manner to create psychological safety. These results were compared with leadership to build psychological safety in general organizations, and recommendations with regard to building psychological safety in school were suggested.