An embodiment provides a deposition mask including an opening area including an opening; a first dummy opening area disposed at a first side of the opening area in a first direction and having a first dummy opening in the first dummy opening area; and a second dummy opening area disposed at a second side of the opening area in the first direction and having a second dummy opening in the second dummy opening area. A first side and a second side of the opening are asymmetrical with respect to a second direction intersecting the first direction, and the first dummy opening and the second dummy opening are symmetrical with the opening with respect to the second direction.