To provide a polyester fiber having a good color tone (b value) and uniform and communicating fine pores, exhibiting an excellent water absorbency and moisture absorbency, generating a very small amount of attached materials to a spinneret even spinning for a long period continuously through the spinneret, and excellent in forming property, and a method for producing the same.

This method for producing the polyester is provided by using a polyester-producing catalyst containing a specific titanium compound and phosphorus compound, adding for blending a specific organic sulfonic acid metal salt in an optional stage before the completion of the spinning process of the polyester, forming the obtained polyester composition to a fiber, then removing the part of the organic sulfonic acid metal salt in the fiber with an aqueous solution of an alkaline compound to form very fine pores in the cross section of the fiber.