To provide a device which can be used for a plurality of grain dryers, enhance the versatility for use, save the space for installation and storage, and can be easily maintained and checked up.

An inlet opening 4 is provided on the side peripheral surface of a cyclone body 3 for dust-containing air W that is forcedly discharged from a dust removal opening 2 of a grain dryer 1. An air discharge opening 5 is provided on the upper surface of the cyclone body and a dust falling opening 6 is provided on the lower surface of the cyclone body. A recovery sack 12 for recovering dust M is provided at the dust falling opening. A plurality of inlet openings are provided on the side peripheral surface of the cyclone body.