Abstract: A trench-digging machine which may normally be moved in a forward direction, includes a frame, a rotatable soil-moving disc mounted on the frame for digging a trench in the soil, thereby throwing up earth, a transmission-gear mounted on the frame, coupled to the rotatable soil-moving disc, and adapted to be powered by an external drive mechanism, a control device mounted on the underside of the frame to regularize the depth of the trench cut by the soil-moving device, a soil-deflector plate mounted on the frame for deflecting earth operatively thrown up by the soil-moving disc, and rotatable and vertically movable trench side-surface processing discs mounted on the frame downstream of the soil-moving disc as defined by the forward direction of movement.