The book provides a detailed and systematic presentation of the foundations of non-relativistic quantum mechanics, designed for persons who are first acquainted with the subject. In the first chapter, as an introduction to quantum mechanics, the specifics of the physics of microobjects are considered. In the second chapter, on the basis of ideas about the amplitudes of probabilities, the problems of the physics of microphenomena are considered (amplitude interference, the principle of superposition, the specificity of the measuring act, causality in quantum mechanics) ; The simplest quantum-mechanical systems - microobjects with two basic states . are analyzed in detail. In the third chapter, the apparatus of quantum mechanics is considered as a synthesis of physical ideas and the theory of linear operators. To demonstrate the operation of the device, a number of specially selected examples and tasks are given. It is intended for students of technical and pedagogical universities, and can also be used by engineers of various profiles.