A mask apparatus includes a mask body including a body front surface and a body rear surface configured to cover at least a portion of a user's face, a fan module disposed at the body front surface, a mask body cover that is coupled to the mask body and defines an inner space accommodating the fan module, a seal coupled to the body rear surface and configured to define a breathing space between the mask body and the user's face. The mask body defines an opening that passes through the mask body and that connects the inner space of the mask body cover to the breathing space. A pressure sensor is disposed in the opening and configured to sense air pressure in the breathing space.