There is provided a wiring substrate including: a core substrate including: a first core substrate including: a plate-shaped first glass substrate; and a first through electrode formed through the first glass substrate; a second core substrate including: a plate-shaped second glass substrate; and a second through electrode formed through the second glass substrate, wherein a diameter of the second through electrode is different from that of the first through electrode; and an insulating member encapsulating the first and second core substrates, and a wiring layer formed on at least one surface of the core substrate. The first and second core substrates are arranged to be separated from each other when viewed from a top.