PURPOSE: A purification method for isophthalic acids is provided to obtain isophthalic acids with high purity and excellent commercial availability and to minimize solvent loss. CONSTITUTION: A purification method for isophthalic acids comprises a step of extracting crude isophthalic acids in the presence of a solvent including water. The crude isophthalic acid includes 0.1 wt% or more of impurities. The impurities include one or more compounds selected from the group consisting of m-toluic acids, benzoic acids, and 3-carboxybenzaldehyde. The ratio of isophthalic acid: solvent is 1:20 - 1:2.
