The article deals with the problematic issues of determining the constitutional law subject matter. Particular attention is paid to the analysis of Oleg E. Kutafin views, who devoted one of his monographic works to the issue in question. The article defines the features of the constitutional law subject matter that distinguish it from other branches of law. The author shares Oleg E. Kutafin opinion that constitutional law "has as its subject matter a two-fold object of regulation," and extends this statement. The author summarizes different scientific approaches to the definition of the subject matter of constitutional law, its scope, current status, place it takes in the system of branches of Russian law, and relationships between them. The author addresses the question of whether the Constitution is exclusively a source of constitutional law or of all branches of law, since it affects all spheres of public life, examines Oleg E. Kutafin views and the views of other scholars who hold different positions on this issue. The author concludes that the constitutional law subject matter is diverse, multi-level, multidimensional, dynamically developing, responding to changes in realities, which confirms conclusions made by Oleg E. Kutafin.