Rosneft signed the deal with Inpex to explore the Magadan-2 and Magadan-3 offshore blocks in the Russian waters of the Sea of Okhotsk.
"Russian Far East one of the key regions of Rosneft operation," Rosneft President Igor Sechin said in a statement. "Signing the agreement with Inpex, one of the leading Japanese oil and gas companies, once again proves Rosneft's commitment to developing its business in the region."
Rosneft estimated the reserve potential for the blocks at around 11.3 billion barrels of oil equivalent.
Inpex will finance exploration through a joint venture with Rosneft. Inpex will have a 33.3 percent stake in the offshore blocks.
Japan imports nearly all of its oil. Sechin said the partnership with Inpex would help with Russian efforts to focus more on the Far East and expand the bilateral economic relationship between Russia and Japan.