To improve a flatness of a glass substrate 3 provided with a plurality of through electrodes 7.

The manufacturing method comprises: a through-hole formation process S1 in which a minimum area separated from a plate glass 1 by cutting is defined as a unit cell, an effective unit cell EU is formed by drilling a plurality of through-holes 4 in the unit cell, a dummy unit cell DU, where the through-hole is not formed, is dispersed in a region where the effective unit cell EU is formed; an electrode inserting process S2 of inserting an electrode member 6 into the through-hole 4; a welding process S3 of welding the plate glass 1 to the electrode member 6 by heating the plate glass 1 up to a temperature exceeding a softening point thereof; and a grinding process S4 of grinding both sides of the plate glass 1 together with the electrode member 6 and exposing a plurality of the electrode members 6 on the both sides of the plate glass 1 in order to make a plurality of through electrodes 7 that are electrically separated from each other.