To achieve a small capacity and realize an easy recyclable state by arranging raking-out gears in such a manner so as not to permit both projections to abut against each other in rotation according to a shredding roll having many projections or teeth forms on an outer periphery surface, and forming such a constitution as to rake out a gypsum board waste from the shredding roll.

When a gypsum board piece 4 is charged from a charging mouth in order to regenerate the gypsum board piece by preventing leaving as it is and diffusion of arsenic and cadmium which are contained in the gypsum board to be used for a wall or the like on building site, the gypsum board piece 4, when passes between a pair of sprocket shaped shredding rolls 1, 2, is pinched by projections 1', 2' of the shredding rolls 1, 2, and cut. Though an amount of a waste of the gypsum increases as the number of times for cutting increases, since the raking gear 3 pivots while engaged with a projection 1' of the tooth of the shredding roll 1 in this case, a tooth tip of the raking-out gear 3 pivots while comes in contact with a tooth bottom 1" of the shredding rool 1, and a raked out waste is prevented from sticking.