PURPOSE: To prevent long foreign matters such as a nail from getting into a slit, by providing a gas inlet orifice into which a gas is flowed from a traverse direction and a ring shaped slit communicated with said gas inlet orifice and injecting a gas upwardly to a desired cylinder.

CONSTITUTION: A gas inlet orifices 7 into which a gas is flowed from a traverse direction and a ring shaped slit 8 communicated with the gas inlet orifices 7 and injecting a gas upwardly are provided to a desired cylinder 1. That is, because a jet orifice of a fluidizing gas is the narrow width ring shaped slit, a fluidized medium such as sand is not almost fallen into the jet orifice and, because a fine powder is received by a nozzle lower end even if invaded and fallen and again blown up if fluidized, the jet orifice is not clogged. In addition, because it is unnecessary to protrude the nozzle upper end above the bottom surface of a furnace and long foreign matters such as a nail is prevented from piercing in and protruding above the bottom surface of the furnace, work can be carried out without trouble even when the furnace bottom is mechanically wiped off.