A mask device according to the present invention comprises: a mask body including an air outlet; an exhaust valve seating portion extending along a circumference of the air outlet in the mask body; an exhaust valve seated on the exhaust valve seating part to selectively open and close the air outlet; and a mask body cover detachably coupled to the mask body, wherein an exhaust valve fixing part for pressing the exhaust valve when the mask body and the mask body cover is coupled is formed on the mask body cover.
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