The book gives a detailed and systematic presentation of the foundations of non-relativistic quantum mechanics, intended for persons who are first acquainted with the subject. In the first chapter, the specifics of the physics of microobjects are considered as an introduction to quantum mechanics. In the second chapter, on the basis of ideas about probability amplitudes, issues of microevent physics are considered (amplitude interference, superposition principle, specificity of the measuring act, causality in quantum mechanics); the simplest quantum mechanical systems are analyzed in detail - microobjects with two basis states.