, also known in English as Tokuno Island, is an island in the Amami archipelago of the southern Satsunan Islands of Kagoshima Prefecture, Japan.
The island, in area, has a population of approximately 27,000. The island is divided into three administrative towns: Tokunoshima, Isen, and Amagi. The largest population center on the island is the town of Kametsu, located along the eastern shore of the island within the administrative town of Tokunoshima. Much of the island is within the borders of Amami Guntō National Park.
The island is known for having the highest birth rates in Japan as well as a significant population of supercentenarians (people living significantly beyond the age of 100).
Tokunoshima is the second largest island in the Amami islands, after Amami Ōshima, and the 15th largest island in Japan. It is more generally included within the Satsunan and Ryukyu archipelagos. Isolated from the other Amami islands, Tokunoshima is located halfway between Amami Ōshima and Okinoerabujima.
The island is of volcanic origin with a length of approximately and width of . Most of the administrative towns of Tokunoshima and Amagi are covered in mountains and rolling hills, with Mount Inokawadake at above sea level as the island's highest peak. Mount Amagidake in the north has a height of . The administrative town of Isen along the southwestern slope of the island is more flat, with fertile soil suitable for agriculture. The coast of the island is largely rugged and rocky with small sandy beaches scattered throughout as well as a series of large cliffs on the southwest edge of the island. The island is surrounded by a coral reef.
A series of large offshore rocks known as Tonbura Rocks are a prominent feature in the ocean off the northeastern coast of the island. The neighboring islands of Amami Ōshima, Kakeromajima, Yoroshima, Ukejima to the northeast and Okinoerabujima to the southwest are all visible from the island. On exceptionally clear days, the twin volcanoes of Iōtorishima, in Okinawa Prefecture, can be seen to the west.