PURPOSE: To provide a grinding device grinding and removing a foreign matter stuck on a metal belt with a grinding roll or applying prescribed polishing.

CONSTITUTION: A grind roll 21 is provided rotatably, approachably, and separably from a roll 7a wound with a metal belt 1 and conveying it, the grinding tool of the grind roll 21 is provided at a constant distance from the roll 7a in the moving direction of the grind roll 21, and the first and second means 25, 27 approaching and separating the grind roll 21 to the roll 7a are connected in series. No backup roll is required when a metal plate is ground, and the device can be made compact at a low cost.