To provide a method of manufacturing a polarizer plate capable of correctly cutting the polarizing plate without cracks that is less likely to extend on the cut surfaces with rare sticking substances to the obtained polarizer plate, and to provide a cutting mat used in this manufacturing method.

A polarizer plate 3 is obtained by fixing a layered original polarizer plate on the main surface of a porous ultrahigh molecular polyethylene resin sheet 1, by attracting it from the other side and cutting the original plate 2 with a blade 4 moving in the thickness direction of the plate by using the porous sheet 1 as a cutting mat. The sheet, obtained by infiltrating a curable fluid, such as ultraviolet-curing ink into the pores of a porous ultrahigh molecular polyethylene resin sheet 1, is especially suitable to use as a cutting mat.