A method for purifying an organic solvent has a first treatment of bringing an organic solvent to be treated into contact with an H-type cation exchanger, and a second treatment of bringing a treated liquid from the first treatment into contact with an anion exchanger and an H-type strongly acidic cation exchanger. According to the present application, the provided method and an apparatus for purifying an organic solvent remove metal impurities of both metal species of monovalent and polyvalent metals in the organic solvent.