A glass substrate includes a first surface and a second surface that are opposite to each other. Multiple through holes pierce through the glass substrate from the first surface to the second surface. Each of five through holes randomly selected from the multiple through holes includes a first opening at the first surface and a second opening at the second surface. The approximate circle of the first opening has a diameter greater than a diameter of the approximate circle of the second opening. The first opening has a roundness of 5 μm or less. Perpendicularity expressed by P=tc/t0 ranges from 1.00000 to 1.00015, where P is the perpendicularity, tc is the distance between the center of the approximate circle of the first opening and the center of the approximate circle of the second opening, and t0 is the thickness of the glass substrate.