PURPOSE: To make a grinder smaller and to prevent various kinds of public pollution by a method wherein a spool runner discharged from a resin molding machine is crushed by a crusher, the crushed matter is carried by air to a grinder through a pipe line, then the ground matter by this grinder is selected and stored.

CONSTITUTION: The spool runner discharged from each molding machine 1 is thrown by a dropping means on a robot into the respective crusher 2 and crushed by the crusher 2 into the form of grains. This crushed material is supplied into a common air carrying pipe 3. The crushed material inserted in this air carrying pipe 3 is supplied by a carrying means due to pressure feed or suction into a collecting cyclone 5. The crushed material supplied into the collecting cyclone 5 is ground by a grinder 4, then selected by a selector 6 and supplied into a hopper 7 to grind the spool runner and stored.