A belt conveyor, comprising a carrying belt unit which includes an endless carrying belt having an upper load-carrying run adapted to carry loads and movable in a direction of transportation, and a plurality of supporting rollers arranged to support and guide said load-carrying run of said carrying belt unit; a friction belt unit which includes an endless friction belt having an upper run which is movable in said direction and is in frictional contact with said load-carrying run of said carrying belt, a plurality of bearing rollers arranged to support and guide said one run of said friction belt, and a plurality of deviating rollers which are located between and offset downwardly relative to said bearing rollers so that said one run of said friction belt moves about said deviating rolle