Method for purifying organic solvent

A method for purifying an organic solvent, comprising contacting an organic solvent containing at least any one or two or more of a magnesium ion, a chromium ion, and a zinc ion with a monolithic organic porous cation exchanger, wherein the monolithic organic porous cation exchanger comprises a continuous skeleton phase and a continuous hole phase, the exchanger has a thickness of a continuous skeleton of 1 to 100 μm, an average diameter of continuous holes of 1 to 1000 μm, a total pore volume of 0.5 to 50 mL/g, and a cation exchange capacity per weight in a dry state of 1 to 6 mg equivalents/g, and cation exchange groups are uniformly distributed in the organic porous cation exchanger,

• and wherein the liquid passage speed of the organic solvent to the monolithic organic porous cation exchanger as a space velocity (SV), is 2 to 100 h−1.