To provide a method for efficiently producing a 2,4-oxazolidinedione from the corresponding 2,4-oxazolidinedione metal salt.

The objective 2,4-oxazolidinedione of formula (IV) is obtained by adding the corresponding 2,4-oxazolidinedione metal salt of formula (III) (R1 and R2 are each H or a lower alkyl; and M is an alkali metal atom) to an aqueous acid solution; normally an aqueous acid solution is added to a solution of the corresponding 2,4-oxazolidinedione metal salt of formula (III) to obtain the objective 2,4-oxazolidinedione of formula (IV); wherein the above solution is a reaction mixture prepared by reaction between a 2- hydroxycarboxylic acid ester of formula (I), urea and a metal alkoxide of formula (II): R4-OM in a solvent.