The article concerns the material developed by the French sociologist and philosopher Bruno Latour. On the example of a number of works belonging to the field of researches called actor-network theory, the author, not setting out to consider the entire theoretical project of Latour on redefining the ontological foundations of social science, undertakes only an attempt to describe the ontology created by the French researcher. The author analyzes a number of key theoretical principles in the concept of Bruno Latour, which are intimately associated with certain ontological assumptions. Consideration of the main ontological categories and concepts involving in a number of B. Latour's texts (actor-network, irreduction, hybrid and others of the kind) is performed to show that the ontology explicated in the works of the French theorist can be regarded as flat ontology. To them, in addition to the ontology of Bruno Latura, it is often added the ontological constructions of M. Delanda, G. Harman, L. Bryant. The author refers to a comparative comparison of the ontologies of B. Latour and M. Deland, produced by the American philosopher, Graham Harman, complementing the analysis of the Laturian ontology with a set of characterizing features. Concluding the review, the author summarizes the consideration of Bruno Latour’s ontology, noting the realism, anti-essentialism and actualism of the philosophical construction of the aforementioned French researcher.