Adachi (written: 安達, 足達, 足立 or あだち in hiragana) is a Japanese surname. Notable people with the surname include:
Adachi clan, a family of samurai
Adachi Morinaga (1135–1200), Japanese warrior from the Adachi clan
Adachi Kagemori (died 1248), Japanese warrior from the Adachi clan and was a son of Morinaga
Akihiko Adachi (born 1965), a Japanese mixed martial artist
Hatazō Adachi (1884–1947), Japanese General
Jeff Adachi (born 1959), Public Defender of San Francisco
Katsuji Adachi, (better known as Mr. Hito) retired Japanese professional wrestler
Adachi Kenzō (1864-1948), Japanese politician and pre-war cabinet minister
Masao Adachi (born 1939), Japanese screenwriter and director
Mitsuru Adachi, Japanese manga artist
Osamu Adachi (born 1987), Japanese actor and singer
Shōtarō Adachi (1901-1995), Japanese photographer
Tsutomu Adachi (1947–2004), Japanese manga artist and the older brother of Mitsuru Adachi
Yuji Adachi, male Japanese popular music guitarist
Yumi Adachi, Japanese actress
Mineichirō Adachi (1870–1934), Japanese judge
Fictional characters:
Adachi Tohru, a character from Persona 4
Adachi Hana, a character from Flunk Punk Rumble