PURPOSE: To obtain the display device which has a dust dumping display function corresponding to actual use and whose efficiency of suction work does not drop, and also, to provide a rugged part in a cylinder by forming plural different spring constant parts in a coil spring for energing to the open air side a piston inserted to be freely slidable into the cylinder.

CONSTITUTION: When dust is not scavenged into a dust collection bag, a piston 40 is held in a prescribed position by a coil spring 50, and a light emission diode 21a is turned on. When dust is scavenged into the dust collection chamber and clogging starts, the piston 40 moves to an opening 30b side against the spring 50. Since a spring constant of the spring part (a) is small, the piston 40 moves quickly and the spring part (a) goes to a closely adhering state, reaches the vicinity of the lead switch 31, the lead switch 31 is turned on by a magnet 44 and a light emission diode 22a is turned on. When clogging advances, the piston 40 further moves the opening 30b side, but since a spring constant of a spring part (b) is large, the piston 40 moves slowly together with clogging and reaches the vicinity of a lead switch 32, and a light emission diode 23a is turned on.