To achieve accurate grinding operation by making a rotary axis of a grinding wheel coincide with a rotary axis of a mount, when a platelike workpiece is ground by a grinding stone provided on the grinding wheel mounted on the mount formed at the tip end portion of a spindle so as to rotate by rotation of the spindle.

The grinding wheel 20 is configured such that the grinding stone 22 is fixed on a free annular portion 24 of a ringlike base 21 having a fixing annular portion 23, the free annular portion 24, an outer wall 26 and an inner wall 25, which are elongated from the fixing annular portion 23 to the free annular portion 24. The mount 19 has a fixing annular portion supporting portion 30 for supporting the fixing annular portion 23 and an inner wall supporting portion 29 for supporting the inner wall 25. The ringlike base 21 is constructed by such a member that the diameter of the inner wall 25 is changed by temperature change. At ordinary temperature, the diameter D2 of the inner wall 25 is formed to be smaller than the diameter D1 of the inner wall supporting portion 29. In the mechanism for mounting the grinding wheel 20, the ringlike base 21 is mounted on the mount 19 in such a state that the diameter D2 of the inner wall 25 has become larger than the diameter D1 of the inner wall supporting portion 29 by heating the ringlike base 21.