A method relates to producing 3-hydroxyadipic acid-3,6-lactone, the method including the following steps (A) and (B): (A) a step of adding an acid to a 3-hydroxyadipic acid-containing aqueous solution to obtain a 3-hydroxyadipic acid-3,6-lactone-containing aqueous solution; and (B) a step of obtaining a 3-hydroxyadipic acid-3,6-lactone extract by bringing the 3-hydroxyadipic acid-3,6-lactone-containing aqueous solution obtained in step (A) into contact with an extraction solvent that is phase-separated from the solution.