A polytrimethylene terephthalate composition including a polyester having a trimethylene terephthalate unit as a main repeating unit, which satisfies all the following requirements : (a) the intrinsic viscosity is 0.50 to 1.60 dL/g; (b) titanium dioxide whose weight distribution of particles having a particle size of more than 1.0 µm is 5.0% by weight or less is contained in an amount of 0.05 to 3.0% by weight; (c) the crystallization exothermic peak top temperature is 165°C or more; and (d) the half-width of the crystallization exothermic peak is 20°C or less. In addition, the invention further encompasses a method for producing a polytrimethylene terephthalate composition using titanium dioxide that has been subjected to a wet-grinding treatment, and also a fiber obtained from the composition. The invention provides a polytrimethylene terephthalate composition, which stabilizes the process in the production of a fiber having small single-fiber fineness by melt-spinning, and is suitable for obtaining a fiber with reduced fluffing.