The present invention relates to a method for preparing high-purity terephthalaldehyde from terephthalaldehyde crystal containing impurities by recrystallization using an antisolvent. Low-purity terephthalaldehyde prepared by a conventional method, which contains a small amount of impurities, is dissolved in a solvent and recrystallized using water as antisolvent to obtain high-purity terephthalaldehyde. The invention is significantly advantageous in using water only as antisolvent. Also, the purification process takes short time and is economical and environment-friendly.