A hand inserting portion is opened at one surface of a casing or at both the one surface and other surface of the casing. The hand inserting portion includes a space in which hands can be accommodated. A high-pressure-airstream generating unit generates a high-speed airstream. A nozzle is provided on each of two opposing sides of the hand inserting portion, from which the high-speed airstream is jetted into the space of the hand inserting portion. The nozzle includes a hole array formed by arranging a plurality of nozzle holes in a row. Air volume of the high-speed airstream is larger at a central portion of the hole array than at other portions of the hole array.