There are disclosed polyester fibers that are composed of at least 90% by weight of poly(trimethylene terephthalate) and have a limiting viscosity of 0.4-2, being characterized by containing a phosphorus compound at 10-250 ppm in terms of weight of elemental phosphorus, containing no more than 3 wt % of cyclic dimers, containing no more than 2 wt % of bis(3-hydroxypropyl) ether copolymerized with the poly(trimethylene terephthalate), and having a birefringence of 0.03 or greater. The polyester fibers are poly(trimethylene terephthalate)-based fibers with excellent whiteness and tenacity, which are obtained by melt spinning of poly(trimethylene terephthalate) resin composition with improved whiteness, melt stability and spinning stability. The polyester fibers of the invention have satisfactory processability and can be mixed with stretch fibers and the like to provide fabrics having functions that cannot be obtained with commonly used polyester fibers and nylon fibers, for various types of clothing products and the like.