A device for levelling a particulate material web (3), such as a wood-fibre mat laid out on a wire (2) and intended for the production of wood-fibre boards, the material web being moved in relation to the device, comprises a rotary shaft (4) and a plurality of elliptic discs (6) mounted thereon. The shaft (4) is adapted to be arranged transversely of the direction of movement of the material web (3) and extends through the centers of the discs (6). The discs (6) are mounted at an axial distance from one another so as to rotate with the shaft (4). About their minor axes, the discs (6) are so inclined in relation to the shaft (4) as to have a circular axial projection.