Adachi is a special ward in the Tokyo Metropolis in Japan. It is located to the north of the heart of Tokyo. The ward consists of two separate areas: a small strip of land between the Sumida River and Arakawa River and a larger area north of the Arakawa River. The ward is bordered by the cities of Kawaguchi, Sōka and Yashio in Saitama and Katsushika, Sumida, Arakawa and Kita in Tokyo. The ward is called Adachi City in English.

Special wards are a special form of municipalities in Japan under the 1947 Local Autonomy Law. They are city-level wards: primary subdivisions of a prefecture with municipal autonomy largely comparable to other forms of municipalities.