The present invention relates to a unified polarizing plate, which employs, as a protection layer of a polarizing film, a transparent film that can simultaneously function as a negative C-plate and transparent protection layer of a polarizing film and has negative refractive index toward thickness direction, thereby simultaneously performing functions as a negative C-plate for optical compensation and as a polarizing plate, and a method for preparing the same. The unified polarizing plate has superior durability at high temperature and high humidity compared to those employing TAC as a protection layer, and improves wide view angle of liquid crystal display having positive refractive index toward thickness direction, when the liquid crystal display device is ON or OFF.