A mask apparatus includes a mask body, a pair of hook mounting portions at side ends of the mask body, a seal coupled to a rear surface of the mask body, and a pair of ear hook portions connected to the hook mounting portions. Each hook mounting portion includes an upper hook mounting portion, a lower hook mounting portion below the upper hook mounting portion, a hook pin at each of the upper hook mounting portion and the lower hook mounting portion, and a through-hole defined in each of the upper hook mounting portion and the lower hook mounting portion. Each ear hook portion includes a strap portion, a first hook portion connecting the strap portion to one of the upper and lower hook mounting portions, and a second hook portion connecting the strap portion to the other of the upper and lower hook mounting portions.