PURPOSE: To save labour and cost for cleaning remarkably by positioning the axis of a supply pipe for an atomized medium under pressure parallel to the axis of heat transfer pipes of a boiler and connecting to one end of the supply pipe a soot blowing pipe which has a plurality of nozzles and providing a drive device connected to its other end.

CONSTITUTION: An arcuate soot blower 6 consists of a supply pipe 10 for an atomized medium under pressure, arcuate soot blower pipe 12 which as a plurality of nozzles 11, and a drive device. The supply pipe 10 is rotated by the drive device with the axial center of the supply pipe 10 as the center, and at the same time the soot blower pipe 12 rotates. Consequently an atomized medium under pressure such as steam, etc. has its effective range of soot blowing with respect to a heat transfer pipe which extends from a circle 5 to a circle 13 because the soot blower is formed in the shape of an arc. Because the dusts which are accumulated near the inlets of the heat transfer pipes 2 are blown obliquely from the lower side on the right or left and from the upper side on the right or left by steam, the dusts can be effectively peeled off and the dusts in the heat transfer pipes 2 are blows off by the turbulent flows developed by the soot blowing.