The objectives of this study are: (1) To find out the relationship between principal's leadership and teacher's performance ; (2) relationship between organizational culture and teacher's performance ; (3)and the relationship between principals' leadership and organizational culture simultaneously to the performance of teachers at the Madinatul Hadid Islamic Middle School in Cilegon. This research is quantitative research, collecting data conducted by using questionnaire and documentation. This research was held at Madinatul Hadid Islamic Middle School in Cilegon, with the population of 60 people with a total sample of 40 respondents. The result of this study are: (1) principal's leadership can affect teacher performance with a correlation coefficient of 0.935; (2) Organizational culture can affect teacher's performance with a correlation coefficient of 0.749; (3) The results of the multiple correlation test shows that the principal's leadership and teacher's organizational culture simultaneously influence the performance of Madinatul Hadid Islamic Middle School teachers in Cilegon at 34.45%, while the remaining 65.55% is influenced by other factors that need further investigation by anyone who is interested. This study shows that a strong principal’s leadership style and an inherent organizational culture will improve teacher performance in teaching.