To provide a flame-retardant polyester which solves problems of prior art, is excellent in flame retardance and hydrolysis resistance and has improved polymerization reactivity.

The flame-retardant polyester includes, based on all the dicarboxylic acid components of polyester, a component derived from a phosphine oxide compound represented by formula (1) in the range of 1-25 mol%, a titanium compound in the range of 50 ppm to 400 ppm as titanium atoms, and a germanium compound in the range of 30 ppm to 300 ppm as germanium atoms (wherein R₁ is one selected from hydrogen, 1-12C monovalent saturated hydrocarbons and 1-12C monovalent aromatic hydrocarbons, and m and n are each an integer of 1-6).