Method for recovering carboxylic acid

A method for recovering a carboxylic acid, which is a method for separating a carboxylic acid from an aqueous solution containing water and a carboxylic acid to obtain a carboxylic acid anhydride, and which comprises: a) a first step in which the aqueous solution is brought into liquid-liquid contact with a preparative extractant containing a component for extracting a carboxylic acid and a diluent; b) a second step in which the preparative extractant obtained in the first step is distilled, the diluent component and water of the preparative extractant are removed by azeotropic distillation, the extractant is separated into a diluent-based extractant component layer and a water layer, the water layer is discharged, and the diluent-based extractant component layer is returned as a reflux to the distillation step, discharging a preparation extraction agent containing carboxylic acid from the bottom of the tower; and c) a third step in which the preparative extractant containing carboxylic acid discharged in the