The present invention is a flame-retardant polyester film including resin layers laminated on both surfaces of a polyester film, wherein the resin layer satisfies 15 ‰¤ (Wc 1 - Wc 2 )/Wc 0 × 100 ‰¤ 99 (where Wc 0 represents the weight of the resin layer, Wc 1 represents the weight of the resin layer after the temperature thereof is raised from 25°C to 600°C in air, and Wc 2 represents the weight of the resin layer after the temperature thereof is raised from 25°C to 800°C in air), and has a non-flammable'gas generating rate of 3 to 40 percent over the range of 180°C to 450°C. The present invention provides a flame-retardant polyester film having an excellent flame retardancy, and adhesive tapes, flexible printed circuits, a membrane switch, a film heater, and a flat cable, each including the flame-retardant polyester film.