to provide a method for the production of a hydroxycarboxylic acid derivative , by which a hydroxycarboxylic acid derivative , which can be reused in various applications , can be obtained from a polyamide at a high yield without consuming a large amount of energy . a method for the production of a hydroxycarboxylic acid derivative , which is characterized by including allowing an alcohol in a supercritical state to act on a polyamide in the presence of a carboxylic acid derivative to depolymerize the polyamide to obtain the hydroxycarboxylic acid derivative .