Ainu (アイヌ・イタㇰ, Ainu-itak), or more precisely Hokkaido Ainu, is a language spoken by a few elderly members of the Ainu people on the northern Japanese island of Hokkaido. It is a member of the Ainu language family, itself considered a language family isolate with no academic consensus of origin. It is classified as Critically Endangered by the UNESCO Atlas of the World's Languages in Danger.

Until the 20th century, the Ainu languages – Hokkaido Ainu and the now-extinct Kuril Ainu and Sakhalin Ainu – were spoken throughout Hokkaido, the southern half of the island of Sakhalin and by small numbers of people in the Kuril Islands. Due to the colonization policy employed by the Japanese government, the number of Hokkaido Ainu speakers decreased through the 20th century, and it is now moribund. A very few elderly people still speak the language fluently, though attempts are being made to revive it.

According to P. Elmer, the Ainu languages are a contact language, having strong influences from various Japonic dialects/languages during different stages of their development, suggesting early and intensive contact between the languages somewhere in the Tōhoku region, with Ainu borrowing a large amount of vocabulary and typological characteristics from early Japonic.