PURPOSE: To facilitate the restore of a remaining material, by shifting a material discharging air valve to send compressed air into a material passage change valve.

CONSTITUTION: A remaining material takeout hose 24 opened into the outlet port 21a of a hopper 21 and a material container 26 are connected to each other by shifting a material passage change valve 25 to cause a blower 20 to inject air backward into the hopper. At the same time, compressed air is introduced into the material passage change valve 25 to restore a remaining material to the container 26 and simultaneously clean the interior of the hopper 21. According to this constitution, the remaining material is all restored by very simple operation, the material which is injected to no avail is extremely decreased and cleaning with an air hose or the like is not needed.