The study’s focus is to identify the conceptual conditions of Latourian ANT as conditions that can be formulated as a specific theory of sign (so-called “material-semiotics”). Therefore, the main aim of the paper is to analyse selected semiotic aspects of the Actor-Network Theory (ANT), namely Latour’s definition of an “actor” as an “actant” and his notion of the “semiotic fabrication” of agency. The interpretation strategy of this essay is a critical comparison of different understandings of the theory of the sign, namely (Saussurean) semiology, (Greimasian) semiotics and (Peircean) semeiotic. Interpretations of these semiotic paradigms comprise the main part of the text along with the evaluation of the Kohn-Latour debate, which can be understood as a more specific development of the Peircean semeiotic. The study points out the controversial aspects of Latour’s acceptance of certain semiotic concepts and their subsequent transposition into the ANT area.