Supervision has an important role in building teacher professionalism that is realized in the form of improving teacher teaching performance in schools. This research tries to dig deeper into the contribution of supervision by the principal to the teaching performance of teachers in elementary schools. This study uses a quantitative descriptive approach. The data was obtained through purposive distribution of questionnaires to 78 teachers from 26 public elementary schools in Plered Sub-District, Purwakarta Regency. The data obtained is then processed with regression to gain the amount of influence from the supervision of the principal on the teacher's performance. The results showed that the supervision conducted by the principal can improve the performance of teachers. These results mean that the teacher's performance can continue to be improved as long as the principal performs his duties as a well supervised.