Abstract: A sheet breaking apparatus for breaking or cutting waste sheet materials according to the invention comprising a pair of endless band-like rotating body, one of which is driven downwardly or in a feeding direction of the sheet materials at a faster speed than that of the other rotating body driven upwardly in a direction opposite to the feeding direction, and cutting blades respectively fixedly arranged on the rotating bodies such that the cutting blades fixed to the downwardly driven rotating body are spaced apart with equal intervals respectively in longitudinal and transverse directions and the cutting blades fixed to the upwardly driven rotating body at least adjacent in the moving direction are not aligned with each other. With the arrangement, fibrous or soft synthetic resin sheets or the like difficult to be mechanically broken are easily and effectively cut or broken into small pieces to make easy next processes for burning, reclaiming or regenerating the waste materials.