A semiconductor device includes: a plurality of semiconductor chips stacked on each other, each of the plurality of semiconductor chips having a semiconductor substrate and a wiring layer; a through electrode penetrating the semiconductor substrate in a thickness direction and electrically connected to each other between the semiconductor chips adjacent to each other; a conductor penetrating the semiconductor substrate in the thickness direction and not electrically connected between the other semiconductor chips; and an insulating separator penetrating the semiconductor substrate in the thickness direction and formed in a shape of a ring surrounding the conductor.