Abstract: A process for producing a polyethylene terephthalate in which the amount of the oligomers, such as cyclic trimer etc., is lower and which causes metal mold staining to occur difficultly. The process comprises an esterification stage in which dicarboxylicacids including mainly terephthalic acid or ester-forming derivatives of such acids are esterified with glycols including mainly ethylene glycol or with ester-forming derivatives of such glycols; a liquid phase polycondensation stage in which the esterified product obtained in the esterification stage is subjected to a polycondensation in a liquid phase containing a polycondensation catalyst and having a content of an alkaline solubilizing agent of 0.