A polarizing plate comprises a polarizer; and at least one optical film on at least one side of the polarizer, wherein the optical film comprises a polyester film, the polyester film has a shrinkage difference between a length shrinkage in a first diagonal direction and a length shrinkage in a second diagonal direction of −0.1% to +0.1% with respect to either the mechanical direction (MD) or the transverse direction (TD) of the polyester film (as a reference direction). An optical display apparatus includes the polarizing plate.