Medvedev arrived there from the Far Eastern city of Yuzhno-Sakhalinsk, located on the Sakhalin island, where he held a meeting with local authorities on the social development of centres of economic growth of the Russian Far East.
The prime minister is expected to visit several social and infrastructure objects on Iturup.
Medvedev regularly visits the Kuril Islands. In 2011, when he was the Russian president, Medvedev visited Kunashir. As a prime minister, he again arrived there a year later. In 2015, Medvedev visited Iturup.
Japan, which disputes the Kuril Islands, referring to them as the Northern Territories, has expressed its protests over Medvedev's visits there.
Russia and Japan have not signed a permanent peace treaty after the end of World War II. The dispute over the Kuril Islands — referred to as the Southern Kurils by Russia and the Northern Territories by Japan — has been one of the main stumbling blocks in the peace talks.
In 1956, Moscow and Tokyo signed a joint declaration that provided for the restoration of bilateral relations after the end of World War II. The Soviet Union also agreed to consider handing over two out four disputed islands — Habomai and Shikotan — to Japan.
Japanese Prime Minister Shinzo Abe has said that he would like to move forward in concluding the peace agreement with Russia.