The purpose of the research. The Russian part of the Saimaa Canal, which has been leased by the Republic of Finland since 1962, has international legal specificity due to the institution of interstate lease of territory. First of all, we are talking about the situation when a state, renting the territory of another state, would find it difficult to fully use it for its own purposes if its jurisdiction in this territory is not implemented in principle. Of course, due to the attributes of state sovereignty, it’s hardly possible to presume that on the territory of state part of its jurisdiction will be transferred to lessee state. However, the international legal basis for the lease of the mentioned territory, formalized by the Agreement between the Russian Federation and the Republic of Finland on the Lease by the Republic of Finland of the Russian Part of the Saimaa Canal and the Surrounding Area and the Order of Navigation through the Saimaa Canal (Lease Agreement) of 2010, confirms the implementation of the international legal presumption of the transfer of part of lessor state powers. The purpose of the research is to identify the limits of the permissible transfer of such powers, and how this may affect the ensuring of jurisdiction and sovereignty by the Russian Federation and the Republic of Finland. Results. The basis of the legal relations on the lease of the Russian part of the Saimaa Canal by the Republic of Finland is the partial transfer of powers in the leased territory from the Russian side to the Finnish side in accordance with Article 15 of the Lease Agreement of 2010. Largely due to such a partial transfer of authority legal relations regarding the lease of the mentioned territory have a long-term, successful character. The implementation of the presumption of the transfer of part of the powers in the legal relations between the Russian Federation and the Republic of Finland regarding the lease of the part of the Saimaa Canal does not entail a violation of the principles of the sovereign equality of states, respect for their sovereignty and non-interference in their internal affairs. In addition, the transfer of part of the Russian Federation powers to the Finnish side is based on extraterritoriality, which, on the one hand, allows the Republic of Finland to implement its legislation on the leased territory to legal relations in which its citizens are participants, on the other hand, it causes a partial restriction of powers of the Russian Federation on application of its legislation within the scope of exterritoriality. The implementation of the presumption of the transfer of part of jurisdictional powers in the mentioned interstate relations is based on the mutual benefit of the Russian Federation and the Republic of Finland, which is material.