A manufacturing method of a metal mask including a plurality of pattern openings includes forming a first depression portion by radiating a first laser beam focused on a plane beyond a subject under processing, and then forming the plurality of pattern openings at a bottom part of the first depression portion by radiating a second laser beam focused on the bottom part of the first depression portion. Because the energy of the second laser beam is less than the first laser beam, manufacturing time of the mask is reduced while the sidewalls of the pattern opening are smooth and may be inclined, to allow for a better deposition of organic emission material onto a large display.