A polarizing plate-cutting device including a laser beam generator configured to emit a laser beam, a scanner including a rotating mirror configured to reflect the laser beam emitted from the laser beam generator, and a housing accommodating the rotating mirror, a condenser lens configured to condense the laser beam reflected from the rotating mirror, and a mounting block onto which the laser beam condensed by the condenser lens is irradiated and to which a polarizing plate is mounted, wherein the mounting block is fixed with respect to the scanner while the polarizing plate is being cut, and wherein the polarizing plate includes a stacking of a base substrate and a polarizing layer, the base substrate being closer to the condenser lens than the polarizing layer, and a heat resistance of the polarizing layer being lower than that of the base substrate.