It is difficult or impossible to elucidate the essence of commercial banks’ financial security without understanding the general problems of economic and financial security, historical premises of the emergence of these concepts and their features in terms of commercial banks. The concept of “financial security” appeared much later in comparison with the concept of “economic security”, which was determined by historical development, and first appeared when analyzing the issue of national security. The mechanism of ensuring the financial security of commercial banks consists of several elements: organization, management, strategy, rating system. It consists from two inseparable parts: the theoretical basis for financial security and a set of practical measures to protect the bank against threats. The theoretical background is the methodological basis to ensure financial security and includes theoretical, means, methods, techniques and economic indicators with quantitative characteristics of limit values and qualitative properties.