To provide a polyester film having favorable optical performances that can achieve high luminance and give a high-quality image without unevenness or defects when the film is used as a member of an LCD, PDP, organic EL, projection display or the like.

The polyester film is an optical biaxially oriented polyester film having a transmittance of 91.0% or more for rays at 400 to 800 nm wavelengths and a ratio of the maximum transmittance (T1) at 400 to 600 nm wavelengths to the maximum transmittance (T2) at 600 to 800 nm wavelengths satisfying T1/T2≤1.02, wherein T1 is the maximum transmittance (%) for rays at 400 to 600 nm wavelengths and T2 is the maximum transmittance (%) for rays at 600 to 800 nm wavelengths.