Provided is a mask assembly. The mask assembly includes a mask frame and a mask. The mask is coupled to the mask frame to distinguish first to third deposition areas from each other. Each of the first and third deposition areas has a first width greater than a reference width in a first direction and a second width less than the first width in a second direction. The second deposition area has a third width less than the first width in the first direction and a fourth width less than the reference width in the second direction.