Abstract: A blade comprises a disc-shaped substrate having a major surface and an outer peripheral edge portion encircling the major surface, and an abrasive grain layer mounted on the outer peripheral edge portion of the substrate. The substrate includes a first disc having a major surface, and a second disc having a major surface which is superposed on that of the first disc. The major surface of the second disc is separated from that of the first disc, thereby defining a clearance between the major surfaces of the first and second discs and correspondingly forming a convex surface region on the outside surface of the substrate. The peripheral portion of the convex surface region is provided with a contact portion where the major surfaces of the first and second discs are slidably in contact with each other.