The article presents conceptual ideas, experience and results of the formation of cognitive motivation in junior-school age group children in extracurricular activities institutions. Such ideas include the junior school-age children motivation's structure, characteristics, basic pedagogical conditions, educational contents, and the criteria of the cognitive motivation's formation. Novelty of the presented research is in defining the realization mechanism of pedagogical conditions for the formation of cognitive motivation in children of junior school age at institutions of supplementary education. The mechanism is based on equal relations and participation of children, parents and the pedagogue, it includes three interlocked stages: motivational-stimulating, substantive, and reflexive-evaluative. In the course of research, conventional theoretical methods as well empirical methods were used, the preferred one of which was a pedagogical experiment. The authors explored the specifics of the formation of cognitive motivation in junior school age children in institutions of supplementary education. The results of the study proved the effectiveness of the proposed concept of the formation of cognitive motivation in junior students. Finally, it was concluded that the proposed concept is feasible and promising. The developed and experimentally tested pedagogical conditions for the formation of cognitive motivation in junior school age children can be widely used in institutions of supplementary education.