Disclosed is a process for purifying a hydroxycarboxylic acid, comprising: a crystallization step of subjecting a hydroxycarboxylic acid aqueous solution to crystallization for purification, a separation step of separating a hydroxycarboxylic acid crystal from a mother liquid, and a washing step of washing the hydroxycarboxylic acid crystal for further purification with a washing liquid, wherein the washing liquid is a hydroxycarboxylic acid aqueous solution. The purified or refined hydroxycarboxylic acid obtained through the above process is suitably used as a starting material for production of a polyhydroxycarboxylic acid. The above process is suitably included in a process for producing a cyclic ester and a process for producing a polyhydroxycarboxylic acid.