PURPOSE: To reduce the height and installation space of a dust collecting apparatus, by mounting a suction pipe for sucking dust accumlated on the lower bottom plate of the dust collecting apparatus and a means for moving the suction pipe along the bottom plate.

CONSTITUTION: Dust separated and collected by an electric dust collecting apparatus 1 and accumulated on the bottom plate 1a thereof is sucked from a suction port 4 positioned directly above the bottom plate 1a and guided to a header pipe 3. At this time, a fan 12 sucks dust at a speed of about 10W20m/s along with gas. The sucked dust is guided to a bag filter or cyclone 2 through a sucking base pipe 2, an expansion joint 9 and a conduit 10 and separated from gas. The suction port 4 is formed so as to be capable of moving to a horizontal direction by a cylinder 5 for horizontal movement and can suck-in dust from the entire region of the bottom plate 1a.