The Sakai (Japanese 酒井氏, Sakai-shi) were a family of the Japanese sword nobility (Buke), descended from Minamoto no Arichika (Seiwa Genji). Arichika had two sons, one of whom, Yasuchika (奏親), took the name "Matsudaira" and the other, Chikauji (親氏), took the name "Sakai".
Hirochika (広親), the son of Chikauji, had two sons who established the two main branches of this family.
With the fiefs of Himeji, Tsuruoka and Obama, each with over 100,000 koku, the Sakai are among the larger Fudai-Daimyō of the Edo period.