To reduce the facility area and the manufacturing cost by providing a rotatable lance tube extending through a casing in parallel with heating tubes in the center of a tube bundle and providing an exhaust pipe disposed on the outlet side of the lance tube with a vacuum blower.

A soot blower 1 for removing soot adhering to the surface of heating tubes constituting a heat exchanger comprises a lance tube 3 disposed in the center of a tube bundle 2 in parallel with the heating tubes while penetrating through a casing 7 with a plurality of ejection openings 59 being made over the entire length. A rotary unit 4 for turning the lance tube 3, a rotary joint mechanism 5a and an on/off valve 6 are arranged sequentially at the upstream end part of the lance tube 3 on the outside of the casing 7. A rotary joint mechanism 5b and a shut valve 15 are arranged sequentially at the downstream end 3b of the lance tube 3 and the shut valve 15 is coupled, on the downstream side thereof, with a cooler 10 through an exhaust pipe 9 and with a vacuum blower 12 through a drain tank 11.