Nakai (written: 中井 or 中居) is a Japanese surname. Notable people with the surname include:
Asakazu Nakai (1901–1988), Japanese cinematographer
Chiharu Nakai (born 1984), Japanese AV actress and glamour model
Daisuke Nakai (born 1989), Japanese professional baseball infielder
Hiroshi Nakai (born 1942), Japanese politician
Kazuya Nakai (born 1967), Japanese actor
Kie Nakai (born 1957), Japanese actress
Kiichi Nakai (born 1961), Japanese actor
Masahiro Nakai (born 1972), Japanese singer, actor and host
Masakazu Nakai (1900–1952), Japanese aesthetician, film theorist, librarian, and social activist
Masutaro Nakai (1895–1969), general in the Imperial Japanese Army
Nakai Chikuzan (1730–1804), Japanese politician
Norio Nakai (born 1952), Japanese writer
R. Carlos Nakai (born 1946), Native American flautist
Shogo Nakai (born 1984), former Japanese football player
Takahiro Nakai (born 1990), Japanese judoka
Takenoshin Nakai (1882–1952), Japanese botanist
Takezo Nakai (born 1949), Japanese former handball player
Yasuyuki Nakai (1954–2014), Japanese baseball player
Yoshikazu Nakai, mathematician, originator of the Nakai conjecture
Yoshiki Nakai (born 1983), Japanese football player
Yoshinori Nakai (born 1960), Japanese artist
Yuki Nakai (born 1970), retired Japanese shooto practitioner and mixed martial artist
Nakai is also a surname of some people from the Punjab, a province in India and Pakistan. They are a sub-cast of Sandhu Jatts and are descendants of Nakai Misl, a principality of the Sikh Empire from 1748 to 1810. For more details refer to pages Nakai Misl, Baherwal Kalan and Sardar Kahan Singh Nakai.
