The formation of teacher's motivation to self-improvement during their professional activity is investigated. The aim of the research is to analyse motivation to self-improvement of physical education teachers in the process of professional activity. Physical education teachers for experimental (EG, n=124) and control (CG, n=124) groups were picked randomly from a pedagogical staff of Ukrainian universities. The Motivation Sources Inventory was used to define motivation to self-improvement. Teachers of CG participated in the traditional in-service training course, EG was trained according to the authorial program. We assume that motivation leads and organizes teachers' activity, provides personal essence and significance of self-improvement, promotes the transformation of externally-formulated aims into inner needs. Basic trends of an effective influence on the intensification of motivation to self-improvement of teachers were: formation of positive guideline for self-improvement in the process of professional activity with the help of specification of requirements to specialists; formation of solid knowledge and skills; actualisation of the need for improvement and professional growth. Intrinsic motivation is important for self-improvement of teachers of physical education in the process of their professional activity. The results of the research show that intrinsic motives dominate among the teachers of CG, which highlights positive attitude to pedagogical activity, and intensify motivation to self-improvement.