For a teacher to be professionally successful, they should possess relevant competencies. A history and legal studies teacher's competency as an integrated entity has not been the subject of scientific researches yet. The paper aims to analyze legal documents as well as scientific literature, generalize and systematize the approaches to understanding the essence and structure of teacher's professional competency. It is considered as a set of specific competencies; a component of teacher's competency; one of its two main competencies. These approaches do not contribute to understanding teacher's competency as a holistic integrated formation; competencies, which are singled out along with teacher's professional competency and should be considered as its organic components. The structure of teacher's competency based on the positions of functional approach is described as a set of components, namely, knowledge of psychology and pedagogy, abilities, skills, emotions, internal motivation, attitudes, moral and ethical values, experience; gnostic, constructive, organizational, communicative, analytical, creative, predictive, projective, informational, pedagogical skills, etc. The teacher's competency is denoted by different terms. Its essence is fully revealed by the term "professional and pedagogical competency", which allows describing teacher's competency as a holistic personal entity belonging to a particular professional teacher, comprehensively characterizing it and serves as a means of achieving pedagogical goals and solving pedagogical tasks, a criterion for a professional teacher's development. Despite certain differences in understanding the essence and the vision of teacher's competency structure, almost all researchers of this problem agree on the fact that the factors of developing a highly competent teacher are high-quality pedagogical education, professional training and lifelong professional development. Rather perspective are further studies on specification of the volume and the content of knowledge, skills and abilities, the values of history and legal studies teachers as components of their competency, as well as experimental confirmation of relevant theoretical positions.