摘要:Teecher is an important component because teacher determines the quality of education so that education and the teacher guidance in all level of education both inside and outside need to be increased and held completely to create a high quality teacher. Besides that, that professional maturity of teacher need to increased continuously. The propessional maturity of teacher is the ability of teacher who has a high responsibility in her/his job. By educational activity, teaching and learning processes, and profession development. A school principal is an educator, a manager, an administrator, and a supervisor. The role of school as a supervison in professional maturity of teacher is done by various efforts.such as: 1) Create the condition of instituonal which is conducive, 2) Give an opportunity and a change to all potencies of teacher, 3) Optimizing the role of leadership, 4) Implementation of clinical supervision. Key words: School principal as supervisor, professional maturity of teacher.