The present application relates to a polymer film and a method for producing a polarizing plate. The present application can provide a polymer film satisfying optical and mechanical durability required in a polarizing plate effectively and capable of forming a polarizing plate without causing bending when applied to a display device, and a method for producing a polarizing plate to which the polymer film is applied. The present application can provide a polymer film capable of realizing the required optical and mechanical durability without causing bending even in a polarizing plate applied to a thin display device and/or a thin polarizing plate, and a method for producing a polarizing plate to which the polymer film is applied.