A method of fabricating a polarizer, the method including, forming a base substrate by sequentially forming a metal layer, a guide layer, a hard mask layer, a sacrificial layer, and a first photoresist layer on a light-transmitting substrate in a panel area and an alignment key area which are spatially separated from each other, forming a first photoresist layer pattern for forming an alignment key pattern in the alignment key area by patterning the first photoresist layer, forming a sacrificial layer pattern in the alignment key area utilizing the first photoresist layer pattern as a mask, and forming a second photoresist layer on a top surface of the sacrificial layer pattern of the alignment key area before removing the sacrificial layer of an aperture area of the panel area.