A sheet-shaped grindstone for grinding a workpiece includes a plurality of segments arranged in an appropriate pattern with sufficient spaces therebetween such that the grindstone becomes flexible. The segments are formed in a manner in which metal powder including diamond grinding grains is sintered to form granular chips, the chips are disposed in a die in such a density that the chips come into mutual contact, and gaps around the granular chips are filled with a resin through application of pressure. The grindstone is more flexible at contact points with a workpiece than are conventional vitrified grinding tools. The grindstone can evade collision of the segments with the workpiece and can grind a curved surface of the workpiece through smooth contact therewith.