PURPOSE: To erase the abrasion of a grinding material, to cause a device to be economical and to prevent the problem of drain processing, etc., from being generated by separating a pin-ball and the grinding material after the pin-ball is grinded, sending the said grinding material with being stirred and cleaned in a cleaning tank while liquid cleanser is added and executing the feeding and circulating of the cleanser in the cleaning tank after being filted.

CONSTITUTION: The pin-ball and grinding material being lifted up in a tube body 2 are sent from a sending port 5 to a separator 6. Then, the grinding material, whose surface is dirty, to fall down and to be separated in the tube body 2 is passed through a grinding material circulating route 8 and one part is detoured and conducted to a detouring circuit 12. The grinding material is conducted to a cleaning tank 13. While the liquid cleanser is added from an injecting port 14 in the head part of the tank, the grinding material is stirred and cleaned by a stirring fan 17. After that, the grinding material is sent from the bottom part of the tank 13 to a tube body 18. Then, the grinding material joins and returns to the circulating route 8 through a returning route 21 by the revolution of a spiral body 20. The dirty liquid cleanser flows out a flowing-out port 15, drawn up to a filter 24 by a pump 23 and filted. After that, the cleanser is conducted to the injecting port 14 and sent into the tank 13.