Horizontally flat-foldable mask having five surfaces

A horizontally flat-foldable mask, the mask comprising:

• a main body having, in a flat folded state, a middle lobe, an upper lobe, a lower lobe, a first fold member extending upward from the middle lobe, horizontally folded from the upper lobe and having a first mid seam line curved or inclined downward from a center toward both sides, and a second fold member extending downward from the middle lobe, horizontally folded from the lower lobe and having a second mid seam line curved or inclined upward from the center toward both sides;
• and
• harnesses fixed to both sides of the main body,
• wherein the first fold member is fully folded using the first mid seam line as a first fold line and the second fold member is fully folded using the second mid seam line as a second fold line.