PURPOSE: To prevent the leakage of abrasives from an insertion hole by providing an electromagnet in a container in opposition to the insertion hole for a work of the container and providing a suction face for sucking the abrasives projected from a projection nozzle on this electromagnet.

CONSTITUTION: Granular abrasives are projected from a projection nozzle 16 for the working part of a work 31 which is inserted into a container 1 through insertion ports 8, 9 to execute working. In this case, the projected abrasives are sucked to the suction face of an electromagnet 10 with the electromagnetic attraction force of the electromagnet 10 provided in the container 1 in opposition to the insertion holes 8, 9. So the abrasives are not leaked to the external part of the container 1 by passing through the insertion holes 8, 9. Consequently, working can be executed by inserting the working part of a work only into the container 1 through the insertion hole from the external part of the container 1, which can be miniaturized.