A method of fabricating a deposition mask includes: preparing a silicon on insulator (SOI) substrate including an upper silicon substrate, a lower silicon substrate, and an insulating layer between the upper silicon substrate and the lower silicon substrate; forming a mask membrane having a plurality of openings by patterning the upper silicon substrate; forming a first protective layer on the upper silicon substrate and a second protective layer on the lower silicon substrate; forming a cell opening by patterning the lower silicon substrate; and removing the first protective layer and the second protective layer.