Provided is a grinding device that prevents a surface of a grinding element from being evenly worn, thereby preventing a drastic decline in grinding capability and a grinding burn. The grinding device 1 according to the present invention includes a support unit 20 attached to a rotary shaft 12 driven by a rotary drive unit 11, so as to be rotatable integrally with the rotary shaft 12, and a grinding element 30 stacked on the support unit 20 and having an uneven grinding surface 31 formed by a plurality of abrasive grains. The support unit 20 has, in a surface thereof, protruding surface portions 21 to be brought into contact with a rear surface of the grinding element 30 when in use, and recessed surface portions 22 recessed from the protruding surface portions 21, alternately located in a circumferential direction. An engagement mechanism 50 which makes an engagement at each of predetermined angular positions so as to retain the grinding element 30 or the support unit 20 moved by a predetermined angle in the
