Abstract: An apparatus for injecting compressed air into a dust collector in a direction opposite to the dust filtering direction to detach adhered dust includes a dust collecting tank with a plurality of filter cloths and a plurality of air injecting pipes installed therein, and an air header secured to the outside of the dust collecting tank by means of fastening members. The air injecting pipes are connected through connecting devices to the circumferential wall of a head cylinder of the air header and a plurality of pulse valves, distribution tubes and solenoid valves are installed on a control box which accommodates a printed circuit board of a control part which periodically admits the supply of the compressed air.