Mask and method for producing same

This mask comprises: a first mask that includes an opening; a second mask that is positioned to the opening of the first mask; and a joining part that joins the first mask and the second mask. The first mask has a first surface, a second surface that is positioned on the opposite side from the first surface, and a side surface that extends from the first surface to the second surface and demarcates the opening. The second mask includes a third surface that is positioned on the first-surface side of the first mask, and a fourth surface that is positioned on the second-surface side of the first mask. Furthermore, the second mask has an effective region that includes a first hole that passes through the second mask, and a peripheral region that is positioned to the periphery of the effective region. The joining part has: a first portion that includes at least a side surface portion, which contacts the side surface of the first mask, and a first surface portion, which contacts the first surface of the first mask;