Abstract: According to the present invention, the rotary axis O--O of a grindstone 22 is inclined to the rotary axis P--P of a semiconductor wafer 20 through an angle .theta. in a direction of the tangent line of the semiconductor wafer. Accordingly, a moving direction of abrasive grains of the grindstone 22 is divided into two including a component force A.sub.1 in the grinding direction and a component force A.sub.2 in the perpendicular direction, and these component forces increase the number of acting abrasive grains, so that the accuracy of the chamfering shape and the surface roughness can be improved. According to the present invention, the peripheral edge of the rotating semiconductor wafer is chamfered while the rotating grindstone 22 is reciprocatingly moved along the inclined grinding surface 24, whereby the number of the acting abrasive grains are increased, so that the accuracy of the chamfering shape and the surface roughness can be improved.