The purposes of this research are to identify and analyze the headmaster leadership and teacher competence in increasing student achievement in school. The research was at Private Islamic Junior High School in Serang, Banten, Indonesia. Researcher is using descriptive and inferential methods. The results of this research showed that there is correlation of the headmaster leadership toward student achievements in school, there is correlation of the teacher competence toward student achievement in school, there are correlation of headmaster leadership and teacher competence towards student achievement in school. Therefore, it can be seen that the headmaster leadership and teacher competence have a strong and significant correlation to increasing student achievement in school. High or low student achievement can be caused by headmaster leadership and teacher competence.