A photolithography method is provided. The photolithography method includes forming a photoresist layer on a wafer, exposing a portion of the photoresist layer by using an exposure device and a mask, and forming a photoresist pattern by removing a non-exposed portion of the photoresist layer. The mask includes a substrate having a main pattern area and a blocking area outside the main pattern area, a main pattern on the main pattern area of the substrate, and a blocking pattern on the blocking area of the substrate. An external circumference of the blocking pattern extends to the maximum area of the mask that may be illuminated by the exposure device or to the outside of the maximum area of the mask.