This article presents a semiological analysis of ideology on the basis of R. Barthes’ semiological theory. The subject of the study is ideology as a semiological system. R. Barthes begins to consider his semiological theory by distinguishing between primary or “natural” semiology and secondary or mythological semiology. Primary semiology represents “natural” language as a simple jumble of senses, concepts and signs. In its turn, mythology is a secondary semiology, which is superstructured over “natural” language. R. Barthes introduces the concept of ideology through the exposure of mythology. In this context, special attention is paid to the semiological system of mythology, on the basis of the analysis of which ideological semiology is derived. The peculiarity of R. Barthes’ consideration of semiology lies in the definition of the signified, the signifier and the sign in relation to the “natural” and mythological semiological systems. The methodology of this study is based on R. Barthes’ semiological theory. C.G. Jung’s psychoanalytical theory and A.F. Losev’s phenomenological theory are applied to the analysis of social mythology. In turn, the social theories of K. Marx, F. Engels, V.I. Lenin and L. Althusser are used to analyze ideology. The scientific novelty of the study lies in the construction of ideological semiology. The hypothesis of the study is that ideology is a semiological system of the third order, which is based on the decomposition of mythological semiology. For “natural” semiology, the signified is a sense, the signifier is a concept, and the sign includes the signified and the signifier in their unity. In mythological semiology, the signified is a form, the signifier is a concept, and the sign is a meaning. Ideological semiology is superimposed over mythological semiology just as mythological semiology is superimposed over “natural” semiology. The main conclusion of this study is that ideology overcomes and unmasks mythology and returns concrete-historical reality in contrast to mythology, which passes off the real for the eternal and metaphysical. As a consequence of the destruction of mythological semiology, a new ideological semiology is formed. The authors’ special contribution is the substantiation and derivation of the semiological system of ideology, in which the signifier is a symbol, the signified is an interest of a social group, and the sign is reality.