To solve such problems of: the efficiency deterioration of a fracture/crushing sorting device due to already-pulverized gypsum powders, many of which are contained in the lumps of collected waste gypsum boards; contamination of gypsum powders in the collected paper slips caused by screen clogging, or increase of a residual amount; deterioration of operating environment or sorting efficiency caused by dust; and facility failure or quality defect of collected gypsum powders caused by contamination of foreign matters.

A system for sorting and treating waste gypsum boards is composed by sequentially disposing: a volumetric feeder having a hopper, bottom belt conveyor and cutting machine; a trommel type primary sieving machine; a fracture/crushing sorting device having biaxial compression-crushing rolls, protruded crushing rolls, two-stage screw conveyors and a screen therebetween; and a secondary sieving machine of vibration type or the like. The waste gypsum board is sorted to gypsum powders, paper slips and residuals to be collected through steps of: performing cutting and volumetric feeding by the volumetric feeder; separating first the gypsum powder by the primary sieving machine; crushing the gypsum powder by the fracture/crushing sorting device and separating paper slips; and separating residuals from the gypsum powder by the secondary sieving machine.