The present invention relates to a biaxially stretched, colored polyester film, which can be widely applied in windowpanes of cars and buildings. This colored film comprises a transparent polyester layer A; a colored polyester layer B formed on one surface of the transparent polyester layer A, the colored polyester layer B containing dyes at the amount of 0.01-10% by weight; and a coating layer C rendered adhesive formed on the surface of the colored polyester layer B opposite to the transparent polyester layer A. When the colored film is adhered to the windowpanes of cars and buildings, it exhibits excellent ultraviolet blocking effect and flame retardance while protecting privacy. Also, even when glass is broken by impacts from the outside, the colored film can prevent a broken piece of glass from being scattered. Thus, the colored film is an improved polyester film having high functionality and multi-functionality.