To provide an easily fibrillating polyester fiber that can feed the product retaining excellent hue, uniformity and high quality for a long period of time.

0.5-2.0 wt.% of a polyoxyethylene polyether and 0.1-1.0 wt.% of an organosulfonic acid metal salt are added to the polyester produced by the polycondensation reaction in the presence of a reaction product between a titanium compound, e.g., an alkyl titanate and a phosphorus compound, e.g., phosphoric acid mono-or diester, as a catalyst for the polyester polycondensation reaction.