To easily suck and recover dust by generating a negative pressure in a cleaning hose using a pressure from the existing air piping of a plant and causing the stoked dust sucked by the cleaning hose to be sucked into the dust chamber of an existing in-plat bag filter-type dust collector and recovered for discarding.

The existing in-plant bag filter-type dust collector 8 sucks dust stacked in a plant by a blower through an extended in-plant duct to cause the settling and stacking of the dust in a dust chamber 10, and recovers the dust into a dust hopper 9 by opening a valve to be discarded. In addition, a negative pressure generating device 15 is arranged in the dust chamber 10 in such a manner that the device 15 is partially introduced into the chamber 10. Further, this negative pressure generating device 15 generates a negative pressure by an ejector effect and causes the suction of the stacked dust by the negative pressure into a cleaning hose 1, with which one of the ends of a center hose is connected, while the other end is introduced into a casing. Thereafter, the device 15 sucks and delivers the dust into the dust chamber 10 and thus the delivered dust is recovered together with dust collected by the dust collector 8 for discarding.