PURPOSE: To promptly manufacture a grindstone of large size and complicated shape at a low cost without using a forming metal mold by mixing a bond and grinding material to obtain a raw material for the flame spraying coating and flame spraying this material on a base stand.

CONSTITUTION: Besides mixed gas of fuel and oxygen supplied through a supply passage 9 to a nozzle 12, a mixed flame spraying raw material composed of a bond and grinding material is sucked out from a cylinder through a supply passage 11 by means of carrying gas which flows through a supply passage 10 and supplied to the nozzle 12. The flame spraying raw material is blown off into a spraying frame 13 along with compressed air from the nozzle 12. A grindstone is formed through blowing thus blown off flame spraying raw material against a base stand 16 of a desired shape.