Motivation of teachers, which holds a strategic position in both teaching and learning process, is deemed important for success of an education system and it should be ensured during supervision as well. The core of this research is to examine the relation between fulfilment levels of supervisory duties of school principals and motivation of teachers. Since existence of two and more variables were aimed to be determined, correlational survey method, which is one of the descriptive survey methods among quantitative research patterns, was used. Universe of this study consists of 14993 teachers, who were all working at schools at different levels such as preschools, primary schools, middle schools and high schools affiliated with the Republic of Turkey Ministry of National Education. The sample of the study consists of 1050 teachers working in these schools who were chosen by random sampling method. “Scale for Determining Fulfillment Levels of Supervisory Duties of School Principals” which was developed by Gündüz (2015) and “Scale for Motivation of Teachers” revised by Polat (2010) were used in this research. Statistical analysis of the research was done via SPSS 14,0. Scale for determining fulfillment levels of supervisory duties of school principals consists of following subdimensions: Supervision of teachers, supervision of education and training, and supervision of venue. Upon conducting the scale on the study group, teachers perceived their principals’ fulfillment levels of supervisory duties at “I agree.” level. Upon conducting the scale for teacher motivation, which consists of intrinsic and extrinsic motivation subdimensions, teachers perceived motivational values at “mostly” level. It is seen that according to education variable, teachers with associate degrees; according to branch variable, teachers of school subjects; and according to variable concerning number of supervisions teachers gone through, teachers with more supervision experience have higher motivation levels. In the conclusion of this research, it is concluded that there is a meaningful relation between fulfillment levels of supervisory duties of school principals and motivation levels covering both intrinsic and extrinsic motivation and that it is a positive meaningful predictor in terms of both intrinsic and extrinsic motivation at fulfillment levels of supervisory duties of school principals and teacher’s motivation levels.