To prevent a casing 3 from being cracked even when the temperature of an outer surface of a heat resistant/corrosion resistant metal casing located outside an injection nozzle of a soot blower nozzle.

When a partition plate 11 is provided at a tip end of an injection nozzle 2 to provide a space section 6, heat is insulated by about 220°C between inner and outer surfaces of the nozzle 2 in contact with the space section 6, and hence an injection medium is prevented from making direct contact with the tip end of the nozzle 2 through the space section 5, and inside temperature at the tip end of the casing 3 is prevented from being excessively cooled with the injection medium mediating the space section 6 and the heat insulation member 4 even when outer surface temperature at the tip end of the casing 3 is 1200°C. Thus, a temperature difference between inner and outer surfaces of the casing 3 is about 200°C and is hence unlikely to receive thermal shock. Further, the casing 3 and the injection nozzle 2 are fixed with a coupling 7, and a recessed portion and a protruded portion 3b, 2b capable of fitting to the casing 3 and the injection nozzle 2 are provided and fixed to prevent the casing 3 from being shifted by rotation of the casing 3 upon the operation of the soot blower.