Polyester fibers having a deformed section are produced from a polyester polymer which is obtained by polycondensing an aromatic dicarboxylate ester in the presence of a catalyst containing a mixture of a Ti component (A) comprising at least one a titanium alkoxide or a reaction product thereof with a specific carboxylic acid or its anhydride with a P compound component (B) represented by the following general formula (III) and/or a reaction product of a Ti compound component (C) with a P compound component (D) represented by the following general formula (IV). The obtained fibers have a favorable color tone and excellent qualities without showing fluffing. (see formula III) (see formula IV)
