A method for producing a purified phthalonitrile is described. The method involves reacting ammonia, oxygen, and xylene in the presence of a catalyst to obtain a product gas containing a phthalonitrile and a cyanobenzamide and then contacting the reaction product gas with an organic solvent to obtain a collection liquid. The collection liquid is distilled by a high boiling point fraction-separating column to obtain a gas that contains the phthalonitrile and the organic solvent from the column top, and to obtain a bottom liquid that contains a cyanobenzamide from the column bottom. The bottom liquid has a phthalonitrile content of 90% by mass or less. The bottom liquid is subjected to combustion, while being kept in a liquid state, and the purified phthalonitrile is obtained by removing the organic solvent from the gas that has been obtained from the column top.