To provide a mask device capable of shortening the stop time of a production line when replacing a mask body by facilitating the attachment/detachment of the mask body to/from a sandblasting device.

The mask device 1 is provided with a bayonet mount 2, a mask body 3, an elastic support member 4 and a bayonet ring 5. The bayonet mount 2 is mounted to the tip of an outer cylinder 92 of the sandblasting device. The mask body 3 is made of disk-shaped metal and provided with a cutout opening 34. The elastic support member 4 is an annular body comprising an elastic pedestal 6 and a cap 7, and the inner peripheral edge part is detachably fitted to the outer peripheral edge of the mask body 3. The bayonet ring 5 is detachably fitted to the elastic support member 4, and has an engaging claw 51 twisted around and engaged with the bayonet mount 2.