A mouth mask is provided, including a flexible sheet body. The flexible sheet body is integrally formed and has a first surface and a second surface opposite to the first surface. The first surface protrudes to form an abutting portion for abutting against a front side of a chin and a supporting portion for abutting against a lower side of the chin. The abutting portion includes a first opening formed on the second surface, and the supporting portion includes a second opening formed on the second surface. The flexible sheet body further includes two connecting portions, and the two connecting portions are located by two opposite sides of the abutting portion and the supporting portion respectively.
