To provide a superfine pulverizing method for waste materials of molded goods by an inorganic binder containing organic fibers which is capable of efficiently pulverizing the waste materials and makes it possible to obtain inorganic superfine products having high quality, excellent transportation efficiency and good handling quality in use.

This method comprises using the waste materials of the molded goods by the inorganic binder containing the organic fibers as objects for treatment, previously subjecting the waste materials to treatment to remove the organic fibers and subjecting the waste materials after the removal treatment to superfine pulverizing. The removal treatment by heating the waste materials of the coarsely crushed matter or pulverized matter of the waste materials at 700 to 1,100°C or the removal treatment by pulverizing the waste materials by a volumetric pulverization type pulverizing machine and subjecting the resultant pulverized matter to treatment to separate the organic fibers by utilizing a specific gravity difference from the pulverized matter.