A deposition mask apparatus, comprising: a frame including a first portion, a second portion facing the first portion across an opening in a first direction, a third portion, and a fourth portion facing the third portion across the opening in a second direction different from the first direction, and including a first surface and a second surface that is located opposite to the first surface; a supporter including a plurality of supporting members that are arranged in the second direction, the supporting member including a first end that is fixed to the first portion on the first surface side and a second end that is fixed to the second portion on the first surface side; and a deposition mask including a third end that is fixed to the third portion on the first surface side and a fourth end that is fixed to the fourth portion on the first surface side, and including a plurality of holes that are located between the third end and the fourth end, wherein the plurality of supporting members include at least a first supporting member that is closest to an intermediate position between the third portion and the fourth portion of the frame and a second supporting member that is located closer to the third portion of the frame than the first supporting member, and when the first surface of the frame is located above the second surface, the first supporting member in a state of warping downward from the frame with a first warping amount supports the deposition mask from below, and the second supporting member in a state of warping downward from the frame with a second warping amount that is smaller than the first warping amount supports the deposition mask from below. a frame including a first portion, a second portion facing the first portion across an opening in a first direction, a third portion, and a fourth portion facing the third portion across the opening in a second direction different from the first direction, and including a first surface and a second surface that is located opposite to the first surface; a supporter including a plurality of supporting members that are arranged in the second direction, the supporting member including a first end that is fixed to the first portion on the first surface side and a second end that is fixed to the second portion on the first surface side; and a deposition mask including a third end that is fixed to the third portion on the first surface side and a fourth end that is fixed to the fourth portion on the first surface side, and including a plurality of holes that are located between the third end and the fourth end, wherein the plurality of supporting members include at least a first supporting member that is closest to an intermediate position between the third portion and the fourth portion of the frame and a second supporting member that is located closer to the third portion of the frame than the first supporting member, and when the first surface of the frame is located above the second surface, the first supporting member in a state of warping downward from the frame with a first warping amount supports the deposition mask from below, and the second supporting member in a state of warping downward from the frame with a second warping amount that is smaller than the first warping amount supports the deposition mask from below.