Abstract: A method for glass substrate chamfering using a metal-bonded outer-surface grindstone 12 for simultaneously processing the end surface and the oblique surfaces of the outer periphery of a doughnut-like glass substrate 1 with a circular hole 1a at the center thereof, and a metal-bonded inner-surface grindstone 14 for simultaneously processing the end surface and the oblique surfaces of the inner periphery are provided; the outer-surface grindstone and the inner-surface grindstone simultaneously grind end surfaces and oblique surfaces of the outer and inner peripheries of the glass substrate, and during grinding, the outer-surface grindstone is sharpened by dressing it electrolytically, and the inner-surface grindstone is sharpened by an electrolytic dressing when not processing as the glass substrate is being replaced.