Public control is an important mechanism for influencing upon public authorities. Its effectiveness ensures social participation within public administration indeed. The effectiveness of public control depends on the quality of its legal regulation and, in particular, upon perfection of mechanisms for public control. Numerous shortcomings of the existing mechanisms for exercising public control are primarily considered due to the legal uncertainty of the guarantees on public control. After all, the guarantees on public control ensure proper functioning of the institution of public control and the effective implementation of the legal status of individuals in the field of public control and the entire social sphere in general. Without their comprehensive analysis, including clarification of its legal nature and essence, it is impossible to build, describe in detail and consolidate legislatively the system of guarantees on public control. Within the frame of the study it has been found that the legal nature of the guarantees on public control and the specifications of their essence largely depend upon the kind of content that is embedded into the concept of the law. The author also believes that the most accurate way to reveal the nature of legal guarantees seems possible with the help of instrumental theory of law, namely being the key concept of “legal means”. In this article the emphasis is stressed onto one of the main reasons for the existence of controversial points and differences in the understanding of legal guarantees, including public control, where there is the ambiguity for the basic category, i. e. “guarantee”. The article also formulates definitions of legal guarantees in the most general sense, as well as from the standpoint of instrumental theory of law. As a result, the author’s understanding of legal guarantees on public control has been introduced.