This article is devoted to the consideration of the problem of loneliness as a phenomenon of the modern world. The individual and his inner world are losing their primacy in the sphere of global political and economic changes in the modern world. The relevance of this study lies in the fact that loneliness is one of the most acute and pressing problems of society today, this problem determines the need for a theoretical basis and a modern concept of the phenomenon (...) of loneliness. This is not only a phenomenon in the life of a person, but also a crucial social phenomenon that requires deep and comprehensive social and philosophical understanding. The aim of this study is to provide theoretical justification for the phenomenon of loneliness as a phenomenon in modern society. The methodological basis of the research on the topic of study was the actual works of domestic and foreign scientists, who consider in their works such a phenomenon as loneliness. In order to achieve the stated goal of research and solve all the tasks, the following research methods were used: analysis, synthesis and generalization of scientific journalism, as well as classification. The circumstances and factors that determine the prevalence and level of loneliness in modern society of the Republic of Kazakhstan are considered. The theoretical meaning of the concept of “loneliness,” its social conditions, as well as the factors of the emergence and spread of the phenomenon of loneliness has been analyzed. This article analyses several current classifications of loneliness in the modern world, developed by domestic and foreign researchers. The emphasis is on causes, symptoms of loneliness as a phenomenon. The study showed that loneliness is an integral part of every person’s life, as well as having its advantages and disadvantages. The practical value of the study lies in the fact that the material considered in the scientific article can be used by psychologists and sociologists of the Republic of Kazakhstan to analyze this phenomenon when working with the population in the state. (shrink)