Abstract: An aromatic polyester is pre-decomposed by heating together with bis-&bgr;-hydroxyethyl terephthalate and/or a low condensate thereof and then, reacted with ethylene glycol to convert the terephthalic acid component of the pre-decomposed product into bis-&bgr;-hydroxyethyl terephthalate and/or a low condensate thereof. The thus obtained solution composition, that is, bis-&bgr;-hydroxyethyl terephthalate solution composition containing ethylene glycol, bis-&bgr;-hydroxyethyl terephthalate and cations and/or anions as impurities is brought into contact with a cation exchanger and/or an anion exchanger to remove cations and anions as impurities to produce bis-&bgr;-hydroxyethyl terephthalate having a small content of ions.