a cleaning device for removing solid impurities from viscous material , in particular molten plastics material , comprising , inside a housing , a filter band for separating out solid impurities which can be moved in the longitudinal direction of the housing . the filter band is wrapped around a curved supporting area of a fixed supporting member at an angle of wrap of preferably approximately 180 °, and is guided on both sides of the curved supporting area in planar supporting areas which lie tangentially and flush against the curved supporting area . to reduce the kinetic resistance of the filter band , the curved supporting area and at least partly the planar supporting areas are provided with channels extending in the direction of transport of the filter band . the plastic material to be cleaned is supplied via a feeding chamber surrounding the supporting area , and after it has been cleaned , is removed via connecting ducts extending from the channels . on the outlet side of the cleaning device the filter band passes through a cleaning solution . in this way , the filter band can be reused . the proposed cleaning device is compact and allows for relatively large effective filtering surfaces .