PURPOSE: To continuously perform the intermittent injection of an abrasive, by communicating one end of each abrasive feeding pipes communicating with a feeding part to a compressed air feeding source via a solenoid valve, communicating the other end of each abrasive feeding pipe with each nozzles further and providing a sensor which detects the presence of a set quantity inside the respective feeding parts.

CONSTITUTION: The body to be worked is set up on the plural nozzles of the cabinet 17 inside of a sand blasting device 10 and a solenoid valve 28 is then made open, and a compressed air pressurizes the abrasive of a feeding part 30 via a dump valve 27, the presence is applied onto an abrasive feeding pipe 24 as well, the abrasive of one time part necessary for polishing the body to be worked of the cabinet 17 inside is injected from a nozzle 12 via an abrasive feeding pipe 24 and the body to be worked is polished. In the case of the abrasive being not dropped into the feeding part 30 for some hindrance or not reaching the set quantity of the abrasive necessary for the one time polishing of an optional body to be worked, the sensor 31 of the feeding pipe 30 inside detects it, cutting off the electrification to a solenoid valve 28 and closing the valve 27.