偏亚砷酸钠是一种无机化合物，化学式为NaAsO₂。

偏亚砷酸钠有剧毒，对人类的致死量约为0.1g。

Sodium arsenite usually refers to the inorganic compound with the formula NaAsO₂. Also called sodium meta-arsenite, it is the sodium salt of arsenous acid. Sodium arsenite also ) Na₃AsO₃, called sodium ortho-arsenite. The compounds are colourless solids.