PURPOSE: To obtain an antistatic polyester fiber, having less reduction in antistatic property in processes of dyeing, alkaline reduction process or repeated washing.

CONSTITUTION: A polyester fiber is constituted with a polyester composition obtained by combining an organic sulfonic acid metal salt of 0.5-10wt.% and an inorganic salt of an alkali or alkaline earth metal of 0.002-2wt.% against the total weight, to a polyester having ethylene terephthalate as a major repeating unit and copolymerized with l-10wt.% of a polyalkylene glycol having a mean molecular weight of 1000-6000.