Apparatus for shredding sheet material including a housing having a front inlet and a rear outlet. A horizontal serrated abutment extends across the lower boundary of the front inlet through which sheet material is fed, as by a pinch conveyor. A horizontal arbor spaced rearward of the abutment rotates within the housing carrying cutting elements having pyramidal tips which trace paths of rotation that cause them to pass downward through the open regions between the serrations in the abutment, piercing the sheet material. Arcuate sections adjacent the tips of the cutting elements cause a ripping action to occur. The shredder operates at a much lower noise level than comparable equipment and provides uniform shredded materials that have interlocking edges.