To provide a polyester film for a mold release film constituted so as to be capable of performing precise inspection in the inspection of a polarizing plate due to a crossed Nichol method and suppressing the transfer of a polyester oligomer to a pressure-sensitive adhesive material layer.

The polyester film for the mold release film is characterized in that a coating layer wherein the number of flaws is 50/m2 or below is provided at least on one side of the polyester film, the amount of a polyester oligomer extracted from the coating layer after heat treatment at 150°C for 10 min is 0.3 mg/m2 or below and the inclination (angle of orientation) of the orientation main axis of the film is 8° or below. The mold release film for a polarizing plate separator is characterized in that a mold release layer is provided on the polyester film. A polyester film for a polarizing plate protecting film comprising the polyester film for the mold release film is also disclosed.