To provide a wet heat resistant polyester fiber having wet heat resistance, without forming coloration and fluffs on the fiber, showing less reduction in its strength even on repeating wet heat treatments and capable of maintaining soft touch feeling and a good color tone.

This wet heat resistant polyester fiber comprises ≥85 mol% polyethylene terephthalate recurring units, containing the amounts of an antimony compound, a cobalt compound and a phosphorus compound satisfying the following formulae (1) to (3) at the same time, and having ≤25 eq/t carboxyl terminal group concentration. (1) 0.5×10-4≤[Sb]≤3.0×10-4(2) 0.1×10-4≤[Co]≤0.6×10-4(3) 0.1×10-4≤[P]≤20.0×10-4. Provided that [Sb] is the content of antimony compound, [Co] is the content of cobalt compound, [P] is the content of phosphorus compound and unit is "mol/mol of acid component".