A deposition mask for forming an organic layer pattern of an organic light emitting diode (OLED) display includes a base member having a first surface facing a substrate of the OLED display, and a second surface facing a side opposite to the first surface, and including a plurality of openings passing through the first surface and the second surface for forming the organic layer pattern. The opening has a pair of first side walls and a pair of second side walls. Each side wall of the openings has an inclination surface inclined with respect to a thickness direction of the base member, and when measuring an inclination angle of the inclination surface with reference to the first surface of the base member, the inclination angle of the first side wall and the inclination angle of the second side wall are different from each other.