PURPOSE: To provide a grinding device capable of automatically grinding the large diameter projected parts of a wire/rod material easily and accurately.

CONSTITUTION: A device in which large diameter projected parts 2 of a wire/rod material 1 provided with the large diameter projected parts 2 are ground for removing them is provided with a positioning mechanism which feeds the wire/ rod material 1 and detects the large diameter projected parts 2 of the wire/rod material 1 in order for positioning them at working points, a rotating grinding wheel which grinds the large diameter projected parts 2 of the wire material 1 with a rotating grinding wheel 15, a mechanism which rotates the wire/rod material 1 in the direction opposite to the rotating direction of the grinding wheel 15, and a delivery mechanism which delivers the wire/rod material 1 after the large diameter projected parts 2 are cut off.