Method for purifying quinolinic acid

Provided is a method for purifying quinolinic acid, comprising the steps of: preparing a fermentation solution containing at least one of quinolinic acid and a salt thereof; removing microbial cells from the fermentation solution; preparing an acidic composition containing a saturation concentration or more of least one of quinolinic acid and a salt thereof, by adding an acid to the fermentation solution; and recovering a crystal of least one of quinolinic acid and a salt thereof from the acidic composition.