The article is devoted to the analysis of the concepts of everyday life in the works of M. Heidegger and R. Barthes. Based on textual and comparative analysis, the author offers her own interpretation of the meaning of the concept of "everyday life" in "Being and Time". In the first section of the study, the author examines Dasein and some structures of its existence, the concept of "das Man" as the basis of inauthentic existence, two modes of Dasein's existence and their connection with the meaning of everyday life. Particular attention is paid to Barthes's work "How to Live Together: Novelistic Simulations of Some Everyday Spaces", which is a collection of his lectures, his concept of "idiorrythmie" in connection with the study of the structure of everyday life. Barthes continues the work begun by Heidegger, but tries to establish and reveal the cultural and ideological influence on human everyday life. To accomplish the tasks, the author uses a methodology that is based on the methods of textual and comparative analysis, as well as the problematization of concepts. The main conclusions of the conducted research are, firstly, the identification of three possible meanings of "everyday life" in the work "Being and Time", secondly, the disclosure of the discourse on everyday life in the framework of R. Barthes's philosophical works, thirdly, an attempt to identify the cultural and ideological influence on the grasp of everyday life by man. Thus, it was established that everyday life itself, as an a priori-ontological condition of human existence, is unchangeable, but only the perception of everyday life by man or his way of grasping everyday life in consciousness changes. In this sense, Barthes continues and brings to a new level the work begun by Heidegger, but he starts not from individual consciousness, but from the life of the "I" with others in everyday life as a space of idiorrhythmes. The discovery of common features of reflections on everyday life in Heidegger and Barthes prompts the author to trace the influence of philosophical texts on changes in the subject of the humanities.