This book, written by Professor Ryogo Kubo, is a textbook of statistical mechanics of an unusual nature. In it, along with a brief summary of the foundations of the theory, there are many problems with instructions and detailed solutions, which are allocated more than half of the volume of the book. Many of the questions of theory that are traditionally presented in statistical mechanics courses are given in the form of examples and problems. In the world educational literature on statistical physics, to date, there are no such problem textbooks that combine a high scientific level with the availability of presentation, although the need for them is very great.