To provide a mask causing no pain in user's ears, forming no gap up to the face, and preventing entering of virus and fine powder to the human body.

This mask includes: a mask part 1; a belt-like band connected to the mask part; a proximal end fastening part provided on the proximal end part closer to the mask side in the band; and a fastening part including a free end side fastening part provided at the free end part. The band 10 has such a length to wind once around the neck or the back of the head and further wind around the face. A slit 3 is formed in a region of the band 10 to be wound round the face. An upper narrow band 8 above the slit 3 presses the upper part of the mask, and also covers a gap up to the cheeks, and a lower narrow band 9 below the slit presses the chin and covers the gap up to the chins, so that the effect of preventing entering of virus and fine powder is high. Since the front of a wearer's mouth is not pressed, the user does not stifle. Further, since a wearer can freely adjust the fastening force of the band by himself, the optimum fastening force can be obtained.