PURPOSE: To prevent the wear of the grindstone of a cam grinder of master cam swing profiling type from affecting the grinding of an object cam, through a simple construction, by providing the grinder with a mechanism for easily compensating to avoid any error in the profile of the object cam which would result from the wear of the grindstone.

CONSTITUTION: A cam grinder comprises a master cam 12 supported in a swingable manner, and touch rollers 15, 16 put in contact with the master cam. A workpiece W is mounted so that it is rotated concentrically to the master cam 12. A grindstone 24 grinds the workpiece W as the master cam 12 is swung. The plural touch rollers 15, 16 different in diameter are coaxially supported so that a prescribed touch roller can be moved into contact with the master cam 12 depending on the change in the diameter of the grindstone 24. The grindstone can be displaced in the direction of cutting feed so as to prevent the diameter of the workpiece W from being changed by the movement of the touch rollers 15, 16.