Abstract: In this article the authors attempted to study the issues of qualification of forms and types of theft of property of persons, defining the criminal law problems in this sphere, as well as the possible solutions for them. The author attempted to generalize and analyze the doctrinal opinions on this issue with certain theoretical conclusions on the moment of completing the crime against property. As an object of studies the authors use legal norms defining legal responsibility for the unlawful acts against property relations and practice of their application. In their studies the authors actively use dialectic approach to scientific cognition in combination to logical, statistical, comparative legal and some other general and specific scientific methods of cognition of a society. The studies have legal novelty, which is due to the compelx of theoretical provisions developed by the authors. In the nearest future these provisions may serve as the basis for the optimization of the Russian legislation in part of defining the final moment of the unlawful acts against propert, both crimes and administrative offences. The article provides a new definition of theft, allowing to avoid many violations of law in the proceedings on administrative and criminal cases. The said provisions are of both scientific and practical value.