A disk-shaped glass plate includes a pair of main surfaces, and an outer circumferential edge surface. A thickness of the glass plate is not larger than 0.6 mm. The outer circumferential edge surface has a circular shape. The outer circumferential edge surface includes a plurality of portions each of which has a blemish, melting, degradation, or alteration. The plurality of portions are formed such that a predetermined space is formed between adjacent portions of the plurality of portions along a circumferential direction. The outer circumferential edge surface has a roundness not larger than 15 μm.