The cleaning device is intended to remove contamination stuck to the underside (12) as well as the carrying surface (11) of the conveyor belt (1) fitted with ribs (14) that move along inside a tunnel housing (3). The cleaning device is installed in the return branch (22), where at least one wiper bar (4) is fastened over the underside (12) of the conveyor belt (1) with a shaft (5) rendered in the load-carrying frame (2) by the side (16) of the conveyor belt (1) within its operating range. The feed area (61) of an ascending conveyor (6) is arranged at the bottom (51) of the shaft (5) its discharge area (62) leads into the dome (32) of the tunnel housing (3). Contamination scraped off by the wiper bar (4) falls into the shaft (5) and is taken by the ascending conveyor (6) between the ribs (14) in the tunnel housing (3), whereby it is returned among the transported material after it passes into the ascending branch (21). Contamination removed by the wiper (8) off the return roller (18), coupled with the wiper bar (4), is returned to the material flow in the same way.
