To provide an antibacterial polyester fiber having good spinnability, good antibacterial activities and excellent color, and hardly causing discoloration (coloring) even if the fiber is subjected to an alkali treatment.

This polyester fiber containing an inorganic antibacterial agent constituted of a phosphoric acid salt carrying silver, and titanium dioxide is regulated so that the content of the antibacterial agent in the fiber may be 0.5-5.0 wt.%. and the content of the titanium oxide in the antibacterial agent may be 30-80 wt.%.