A mask apparatus includes a mask body that defines a suction hole and a discharge hole, a face guard detachably coupled to the mask body by magnetic force and configured to contact a face of a user, and an air cleaning module configured to filter external air and to supply the filtered air to a breathing space. The face guard includes a coupling portion facing a rear surface of the mask body. The coupling portion includes a magnetic body and a magnetic body mounting portion that receives the magnetic body. The magnetic body mounting portion includes a mounting portion body that protrudes forward from an outer surface of the coupling portion and an insertion guide rib disposed inside the mounting portion body, where the mounting portion body and the insertion guide rib are spaced apart from each other to thereby define an insertion hole that receives the magnetic body.