A grinding device and a grinding method for grinding at least one knife. The grinding device includes a frame with a knife holder and a grinding unit comprising a grinding head, a grinding head holder, and a grinding head drive assembly. The grinding unit can selectively be connected with the frame or can be disconnected from the frame and can be placed on a cutting assembly with knives to be ground. In both operating modes the grinding head drive assembly rotates the grinding head and moves the rotating grinding head with respect to the grinding head holder.