A mask for lithography and a method of manufacturing the same. The mask may include a substrate, a reflection layer formed of a material capable of reflecting electromagnetic rays on the substrate and an absorption pattern formed in a desired pattern such that absorbing regions with respect to electromagnetic rays and windows through which electromagnetic rays pass are formed, wherein the absorption pattern includes at least one side surface that is adjacent to the window and is inclined with respect to the reflection layer. The method may include forming a reflection layer which is formed of a material capable of reflecting electromagnetic rays on a substrate, forming an absorption layer which is formed of a material capable of absorbing electromagnetic rays on the refection layer, and patterning the absorption layer to form an absorption pattern with at least one side surface adjacent to a window that has an inclined side surface with respect to the reflection layer.