The book is devoted to the application of group theory methods in various fields of theoretical physics. The basic concepts and results of group theory are presented, which are then applied to a wide variety of areas of physics, such as atomic spectrum theory, molecular structure, solid-state theory, nuclear physics, and particle theory. The book is intended for researchers, Those who want to systematize or expand their knowledge and prepare for reading original works Using group theory, as well as for postgraduate and senior students of universities and physico-technical universities , Specializations in Theoretical Physics .