Arai (written: 新井 or 荒井) is a Japanese surname.

"新井" means "new residence.”

Notable people with the surname include:

• Akino Arai (新居 昭乃, born 1959), Japanese singer and lyricist
• Alberto Arai (1915–1955), Mexican architect and writer
• Atsushi Arai (荒井 陸, born 1994), Japanese water polo player
• Etsuji Arai (新井 悦二, born 1957), Japanese politician, younger brother of Iemitsu Arai
• Hakuseki Arai (新井 白石, 1657–1725), Japanese scholar and politician
• Haruhiko Arai (荒井 晴彦, born 1947), Japanese screenwriter
• Hideki Arai (新井 英樹, born 1963), Japanese manga artist
• Hirofumi Arai (新井 浩文, born 1979), Japanese actor
• Hiroto Arai (新井 博人, born 1996), Japanese footballer
• Hiroyuki Arai (荒井 広幸, born 1958), Japanese politician
• Iemitsu Arai (新井 家光, born 1955), Japanese politician, older brother of Etsuji Arai
• Ikunosuke Arai (荒井 郁之助, 1836–1909), Japanese samurai
• Izumi Arai (新井 泉) (born 1964), birthname of Japanese singer and actress Minami Takayama (高山 みなみ)
• Kenichiro Arai (新井 健一郎, born 1972), Japanese male professional wrestler
• Kenji Arai (新井 健二, born 1978), Japanese football player
• Kikuo Arai (新井 規矩雄, born 1943), Japanese male golfer
• Kiyoko Arai (あらい きよこ), Japanese manga artist
• Kozo Arai (荒井 公三, born 1950), Japanese retired football player
• Maki Arai (新井 麻葵, born 1982), Japanese women's tennis player
• Marie Arai (荒井 万里絵, born 1981), Japanese female pair skater
• Masao Arai (荒井 政雄, born 1949), Japanese male wrestler
• Masaru Arai (新井 優, born 1952), Japanese astronomer
• Matsuri Arai (荒井 祭里, born 2001), Japanese diver
• Motoko Arai (新井 素子, born 1960), Japanese science fiction writer
• Naoto Arai (新井 直人, born 1996), Japanese footballer
• Nobuaki Arai (荒井 修光, born 1973), Japanese baseball player
• Nobuo Arai (新井 信男, 1909–1990), Japanese male freestyle swimmer
• Noriko Arai (荒井 のり子, born 1973), Japanese female wheelchair racer
• Noriko H. Arai (新井 紀子, born 1962), Japanese mathematical logician and artificial intelligence researcher
• Ryohei Arai (disambiguation), multiple people
• Arai Ryoichiro (新井 領一郎, 1855–1939), Japanese businessman
• Ryōji Arai (荒井 良二, born 1956), Japanese illustrator
• Ryota Arai (新井 良太, born 1983), Japanese baseball player
• Sasagu Arai (荒井 献, born 1930), Japanese Biblical scholar
• Satomi Arai (新井 里美, born 1980), Japanese voice actress
• Satoshi Arai (荒井 聰, born 1946), Japanese politician
• Shigeo Arai (新井 茂雄, 1916–1944), Japanese male freestyle swimmer
• Shōgo Arai (荒井 正吾, born 1945), Japanese politician
• Shota Arai (disambiguation), multiple people
• Shoichi Arai (荒井 昌一, 1965–2002), Japanese professional wrestler promoter
• Takahiro Arai (新井 貴浩, born 1977), Japanese baseball player
• Takako Arai (新井 貴子, born 1990), Japanese beauty pageant contestant
• Tatsunori Arai (新居 辰基, born 1983), Japanese football player
• Tatsuo Arai (長井 研究室), Japanese engineer
• Tatsuya Arai (新井 辰也, born 1988), Japanese football player
• Toshi Arai (新井 敏弘, born 1966), Japanese rally driver and team owner
• Yuko Arai (新井 祐子, born 1973), Japanese female fencer
• Yumi Arai (荒井 由実) (born 1954), birthname of Japanese musician Yumi Matsutoya (松任谷 由実)
• Zack Arai, Japanese adult video director