A deposition mask that prevents the occurrence of defects when forming an encapsulation film or securing a long lifespan of the encapsulation film, a method of manufacturing a display apparatus by using the deposition mask, and a display apparatus manufactured by the method. The deposition mask has a first portion and a second portion, the second portion being thicker that the first portion; at least one opening in the first portion, deposition materials being passed through the opening; and a plurality of through-holes in the first portion adjacent to and surrounding the opening, the through-holes extending from an upper surface to a lower surface of the first portion, light being passed through the opening and the plurality of through-holes to irradiate the deposition materials.