A dustproofing device for use with a linear module includes a dustproofing band disposed around a first pulley pivotally connected to a first end unit and a second pulley pivotally connected to a second end unit. Two ends of the dustproofing band fixedly connect to a fixing platform. The fixing platform fixedly connects to a moving platform of the linear module. A top lid is fixedly disposed on the first end unit and the second end unit and covers the fixing platform, so as for the dustproofing device to be mounted on the linear module. Since the linear module is covered with the first end unit, a first lateral lid, the second end unit and the top lid, not only is the linear module rendered dustproof, but it also takes less time than before to mount the dustproofing device in place.