白芥（学名：Sinapis alba），为十字花科白芥属下的一个植物种。

White mustard (Sinapis alba) is an annual plant of the family Brassicaceae. It is sometimes also referred to as Brassica alba or B. hirta. Grown for its seeds, mustard, as fodder crop or as a green manure, it is now widespread worldwide, although it probably originated in the Mediterranean region.