The present invention provides: a palladium-containing supported catalyst which is used for producing an α,β-unsaturated carboxylic acid from an olefin or an α,β-unsaturated aldehyde in high selectivity; a method for manufacturing the catalyst; and a method for producing an α,β-unsaturated carboxylic acid in high selectivity. In particular, the present invention resides in a method for manufacturing a palladium-containing supported catalyst for producing an α,β-unsaturated carboxylic acid from an olefin or an α,β-unsaturated aldehyde, comprising the step of reducing palladium oxide contained in a catalyst precursor wherein at least the palladium oxide is supported on a carrier. By using such a palladium-containing supported catalyst, an α,β-unsaturated carboxylic acid is produced through liquid-phase oxidation of an olefin or an α,β-unsaturated aldehyde with molecular oxygen.