In the extended course of lectures delivered at the Higher School of Physics of Rosatom State Corporation in May 2014 . After the presentation of the basic concepts of modern cosmology and ideas about the well-studied periods of evolution of the early Universe - the era of neutrino hardening and the era of primary nucleosynthesis - unresolved problems are also considered. These include the problem of the nature of dark matter and the mechanism of its generation and the problem of the origin of the asymmetry between matter and antimatter in the Universe. To facilitate the reading of these parts, the application describes the properties of neutrinos, the main of which are neutrino oscillations. A range of issues related to the era preceding the hot stage of evolution and responsible for the generation of primary inhomogeneities, from which structures were subsequently formed - the first stars, galaxies, clusters of galaxies. As the most plausible hypothesis about this stage, the theory of cosmological inflation is presented, but its alternatives are also briefly considered. This electronic edition was prepared on the basis of the printed edition of the same name, published in the Publishing House of MPEI in 2015. For researchers, graduate students and physics students.