A mask apparatus includes a mask body having a fan module, a seal defining a breathing space, a pressure sensor sensing air pressure in the breathing space, a mask body cover coupled to the mask body, and a controller that controls a rotation speed of the fan module based on pressure values. The controller is configured to determine breathing information including a maximum pressure value and time point, and a minimum pressure value and time point, determine a breathing state of a user based on the breathing information, determine whether the breathing state is a steady state, determine a tidal volume of the user based on the breathing information, and control the rotation speed of the fan module based on the tidal volume.