In end face grinding processing for a disk-shaped glass substrate, the rotation axis of a rotating grinding wheel is inclined with respect to an axis orthogonal to a principal surface of the substrate, and a pair of chamfered faces of the glass substrate are simultaneously ground. The grinding wheel is a groove-shaped grindstone having a pair of chamfered face grinding regions for grinding the chamfered faces of the glass substrate. The pair of chamfered face grinding regions are characterized by, with a contact point between the glass substrate and the grinding wheel, which is located on a straight line connecting the center of the glass substrate and the rotation axis of the grinding wheel, as a reference, being configured from a chamfered face grinding region (A) which is in contact with the chamfered face of the glass substrate on the front side in the rotation direction of the grinding wheel, and a chamfered face grinding region (B) which is in contact with the chamfered face of the glass substrate on the back side in the rotation direction of the grinding wheel, and the aperture angle of the chamfered face grinding region (A) is smaller than the aperture angle of the chamfered face grinding region (B).