The purpose of this study is to investigate the effects of career(principal, teacher, professional career) and degree elements(degree level, degree type) on the principal leadership and take a look at the important elements in the principal recruitment using the status and level of schools of middle school data surveyed by KEDI. Analysis result shows that professional career have a significant negative effect on transformational and instructional leadership. Other career variables such as teacher and princiapal/vice principal career appears non-significantly. In case of degree variables, education administration or educational psychology variable has a significant positive effect on transformational leadership. However, masters degree does not appear significantly. Thus, educational administration or educational psychology degree could be an important factor increasing principal leadership. Principal gender was not significant factor and public school principals shows higher leadership score than private school ones.