Disclosed is a palladium-containing catalyst for producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde in high productivity. Also disclosed are a method for producing such a catalyst, and a method for producing an α, β-unsaturated carboxylic acid in high productivity. Specifically, a palladium-containing catalyst is produced by a method containing a step in which palladium in an oxidation state is reduced by a compound (A) which is represented by the following formula (1).