The aim of the article is to study a phenomenon that is undergoing evolutionary changes in the theory of administrative process, namely, the subject of administrative procedural legal relations based on the concepts of the general theory of law about the subject of legal relations, taking into account the peculiarities of the sectoral orientation of the norms of administrative procedural and substantive administrative law. Accordingly, the tasks of the work are: determination of the nature of the obligatory and optional subject of the administrative procedural legal relationship; the relationship between the subject of the administrative procedural relationship and the administrative legal relationship The goals and objectives of the study determined the research methodology, which is based on general philosophical heuristic methods, as well as the method of comparative analysis, system-structural method. The principal result of this article is the idea that the understanding of the subject of an administrative procedural legal relationship correlates with the concept of the subject of an administrative legal relationship and, accordingly, administrative legal personality is a condition for the presence of an administrative procedural legal personality. However, administrative procedural capacity as an element of legal personality depends not only on age and legal limiting factors, but also on procedural acts of jurisdictional bodies, which, in cases established by law, can endow a person with administrative procedural capacity within the framework of judicial discretion. At the same time, the synthetic definition of the subject of the administrative procedural relationship entails the heterogeneity of the subject composition of the administrative procedural relationship. In this regard, the logic of the analysis of the declared phenomena presupposes their comparison with similar structural elements of other types of procedural legal relations and a new look at the theory of the subject of procedural legal relations in the general theoretical sense.